Using confidential corporate income tax return data, this paper investigates the association between book-tax non-conformity (measured as book-tax differences) and tax-loss carryforwards (TLCFs). I find that TLCFs are positively associated with temporary and permanent book-tax differences. Only firms with positive pre-tax book income and negative taxable income (double-picture firms) drive the positive association between TLCFs and temporary book-tax differences. Conversely, the positive association of TLCFs and permanent book-tax differences is present for double-picture firms and the remaining firms. The results suggest that double-picture firms, which feature high TLCFs compared to their size and to the remaining firms, use temporary book-tax differences to report a lower taxable income than pre-tax book income. Thus, this paper contributes to the understanding of the drivers of rising TLCFs. This is important, as offsetting TLCFs against future profits jeopardizes a country’s tax revenue.
{"title":"Accumulation of Tax-Loss Carryforwards: The Role of Book-Tax Non-Conformity","authors":"Saskia Kohlhase","doi":"10.2139/ssrn.2794992","DOIUrl":"https://doi.org/10.2139/ssrn.2794992","url":null,"abstract":"Using confidential corporate income tax return data, this paper investigates the association between book-tax non-conformity (measured as book-tax differences) and tax-loss carryforwards (TLCFs). I find that TLCFs are positively associated with temporary and permanent book-tax differences. Only firms with positive pre-tax book income and negative taxable income (double-picture firms) drive the positive association between TLCFs and temporary book-tax differences. Conversely, the positive association of TLCFs and permanent book-tax differences is present for double-picture firms and the remaining firms. The results suggest that double-picture firms, which feature high TLCFs compared to their size and to the remaining firms, use temporary book-tax differences to report a lower taxable income than pre-tax book income. Thus, this paper contributes to the understanding of the drivers of rising TLCFs. This is important, as offsetting TLCFs against future profits jeopardizes a country’s tax revenue.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85506442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Schulz (2016) replicates the findings of van Binsbergen, Brandt, and Koijen (2012)--henceforth, BBK--and agrees that the average pretax returns on short-term dividend strips are higher than those of the index, but argues that the after-tax returns are not. He thus provides a possible economic interpretation of the results in BBK: taxes. Schulz (2016) estimates the differential tax rates of dividends versus capital gains from ex-dividend day returns. We show that these estimated tax rates are suspect and imprecisely measured, peaking at over 100 percent in some periods. The results in BBK are robust to using tax rates from the literature (Sialm 2009). The arguments in Schulz (2016) thus crucially depend on implausibly large tax estimates. We further discuss two other financial market imperfections discussed in the literature and show that they are also unlikely to explain the results in BBK.
{"title":"On the Timing and Pricing of Dividends: Reply","authors":"Jules H. van Binsbergen, R. Koijen","doi":"10.2139/ssrn.2787713","DOIUrl":"https://doi.org/10.2139/ssrn.2787713","url":null,"abstract":"Schulz (2016) replicates the findings of van Binsbergen, Brandt, and Koijen (2012)--henceforth, BBK--and agrees that the average pretax returns on short-term dividend strips are higher than those of the index, but argues that the after-tax returns are not. He thus provides a possible economic interpretation of the results in BBK: taxes. Schulz (2016) estimates the differential tax rates of dividends versus capital gains from ex-dividend day returns. We show that these estimated tax rates are suspect and imprecisely measured, peaking at over 100 percent in some periods. The results in BBK are robust to using tax rates from the literature (Sialm 2009). The arguments in Schulz (2016) thus crucially depend on implausibly large tax estimates. We further discuss two other financial market imperfections discussed in the literature and show that they are also unlikely to explain the results in BBK.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90831010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerous empirical studies have analysed the influence of corporate taxation on the location of intangible assets within a company group. However, the previous literature has rather focused on studying the impact of taxation on patent location choices assuming that these assets represent the rest of intangibles as well. This paper complements previous studies by estimating and comparing the tax elasticities of two different types of intangibles - patents and trademarks. We employ data on European and US patent and trademark applications in the period of 1996-2012 and estimate a multinomial logit model that incorporates various observed and unobserved factors of the intangible's location choice. According to our main findings, trademarks are more sensitive to changes in taxation as compared to patents. This implies that firms use trademarks more eagerly for tax planning purposes than patents.
{"title":"Corporate Taxation and Location of Intangible Assets: Patents vs. Trademarks","authors":"O. Dudar, Johannes Voget","doi":"10.2139/ssrn.2753656","DOIUrl":"https://doi.org/10.2139/ssrn.2753656","url":null,"abstract":"Numerous empirical studies have analysed the influence of corporate taxation on the location of intangible assets within a company group. However, the previous literature has rather focused on studying the impact of taxation on patent location choices assuming that these assets represent the rest of intangibles as well. This paper complements previous studies by estimating and comparing the tax elasticities of two different types of intangibles - patents and trademarks. We employ data on European and US patent and trademark applications in the period of 1996-2012 and estimate a multinomial logit model that incorporates various observed and unobserved factors of the intangible's location choice. According to our main findings, trademarks are more sensitive to changes in taxation as compared to patents. This implies that firms use trademarks more eagerly for tax planning purposes than patents.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85195836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Campbell, Jenny Xinjiao Guan, Oliver Zhen Li, Zhenlong Zheng
We examine the association between CEO severance pay (i.e., payment a CEO would receive if s/he is involuntarily terminated) and corporate tax planning activities. We find that CEO severance pay is positively associated with corporate tax planning, consistent with CEO severance pay providing contractual protection against managers' career concerns and thereby inducing otherwise risk-averse managers to engage in incremental levels of tax planning. This result holds under an instrumental variable approach and propensity score matching, and survives alternative measures of CEO severance pay and corporate tax planning. Finally, we find that severance pay provides stronger tax planning incentives in situations where managers are expected to face greater career concerns—when they are less experienced, when they face stronger shareholder monitoring, and when they manage firms with higher idiosyncratic volatility. Overall, our results suggest that CEO severance pay represents a form of efficient contracting with otherwise risk-averse managers.
{"title":"CEO Severance Pay and Corporate Tax Planning","authors":"J. Campbell, Jenny Xinjiao Guan, Oliver Zhen Li, Zhenlong Zheng","doi":"10.2139/ssrn.2802426","DOIUrl":"https://doi.org/10.2139/ssrn.2802426","url":null,"abstract":"\u0000 We examine the association between CEO severance pay (i.e., payment a CEO would receive if s/he is involuntarily terminated) and corporate tax planning activities. We find that CEO severance pay is positively associated with corporate tax planning, consistent with CEO severance pay providing contractual protection against managers' career concerns and thereby inducing otherwise risk-averse managers to engage in incremental levels of tax planning. This result holds under an instrumental variable approach and propensity score matching, and survives alternative measures of CEO severance pay and corporate tax planning. Finally, we find that severance pay provides stronger tax planning incentives in situations where managers are expected to face greater career concerns—when they are less experienced, when they face stronger shareholder monitoring, and when they manage firms with higher idiosyncratic volatility. Overall, our results suggest that CEO severance pay represents a form of efficient contracting with otherwise risk-averse managers.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87115372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We examine how a comprehensive change in book-tax conformity affects firms' reporting behavior. To this end, we exploit a Reform Act as a quasi-natural experiment which implied a decrease in book-tax conformity in Germany in 2010. In particular, this reform allows firms to exercise tax accounting options independently from financial accounting. Our study builds on a unique dataset of linked individual financial statements and actual tax return data. It covers roughly 150 incorporated firms for the years 2008 to 2012. Exploiting the exceptional change in conformity, we contribute to the ongoing debate on the impact of booktax conformity. Our results show that profitable companies, which have a clear tax sheltering incentive, actually use the newly introduced reporting leeway to manage taxable income downwards. This is especially attributable to companies exploiting favorable tax depreciation rules. Moreover, we find larger opportunistic tax reporting responses for small companies with less complex and predominantly domestic group structures. In addition, we observe that a decrease in book-tax conformity induces a decrease in the general persistence of taxable income, but at the same time gives rise to higher financial earnings persistence. This corroborates our finding of increased tax sheltering activity in post reform years.
{"title":"Book-Tax Conformity and Reporting Behavior – A Quasi-Experiment","authors":"Marcia Evers, Ina Meier, Katharina Finke","doi":"10.2139/ssrn.2760323","DOIUrl":"https://doi.org/10.2139/ssrn.2760323","url":null,"abstract":"We examine how a comprehensive change in book-tax conformity affects firms' reporting behavior. To this end, we exploit a Reform Act as a quasi-natural experiment which implied a decrease in book-tax conformity in Germany in 2010. In particular, this reform allows firms to exercise tax accounting options independently from financial accounting. Our study builds on a unique dataset of linked individual financial statements and actual tax return data. It covers roughly 150 incorporated firms for the years 2008 to 2012. Exploiting the exceptional change in conformity, we contribute to the ongoing debate on the impact of booktax conformity. Our results show that profitable companies, which have a clear tax sheltering incentive, actually use the newly introduced reporting leeway to manage taxable income downwards. This is especially attributable to companies exploiting favorable tax depreciation rules. Moreover, we find larger opportunistic tax reporting responses for small companies with less complex and predominantly domestic group structures. In addition, we observe that a decrease in book-tax conformity induces a decrease in the general persistence of taxable income, but at the same time gives rise to higher financial earnings persistence. This corroborates our finding of increased tax sheltering activity in post reform years.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83589498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study is to experimentally investigate an analytical model of tax compliance, assuming a game-theoretic situation between a taxpayer and a tax auditor. Specifically, we focus on the following three research questions. First, would the taxpayer’s behavior change if the tax auditor is a human or a computer, ceteris paribus? Second, how do changes of the tax rate affect the taxpayer’s and auditor’s behavior? Third, what influence does personality have on the tax compliance of taxpayers?The main results of this study are as follows. First, the taxpayer evades less when the tax auditor is a human than when it is a computer. Second, a decrease in the tax rate can increase the taxpayer’s tax compliance behavior. Third, the compliance rate increases among taxpayers who are younger, more trustworthy, and have lower levels of strategic reciprocity.
{"title":"Tax Compliance with Strategic Auditors: An Experimental Study","authors":"Yutaro Murakami, S. Taguchi","doi":"10.2139/ssrn.2680463","DOIUrl":"https://doi.org/10.2139/ssrn.2680463","url":null,"abstract":"The purpose of this study is to experimentally investigate an analytical model of tax compliance, assuming a game-theoretic situation between a taxpayer and a tax auditor. Specifically, we focus on the following three research questions. First, would the taxpayer’s behavior change if the tax auditor is a human or a computer, ceteris paribus? Second, how do changes of the tax rate affect the taxpayer’s and auditor’s behavior? Third, what influence does personality have on the tax compliance of taxpayers?The main results of this study are as follows. First, the taxpayer evades less when the tax auditor is a human than when it is a computer. Second, a decrease in the tax rate can increase the taxpayer’s tax compliance behavior. Third, the compliance rate increases among taxpayers who are younger, more trustworthy, and have lower levels of strategic reciprocity.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89007774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The question of why some companies pay more taxes than others is a widely investigated topic of interest. One of the famous suspect explanations is a phenomenon called tax avoidance. We develop a holistic theoretical concept of influences on corporate tax planning through a series of 19 in-depth German tax expert interviews. Our findings show that three distinct hurdles in the tax planning process can explain different levels of tax expense across companies. Those three hurdles are which tax planning methods are. available (defined by business context), desirable (given via aims of tax planning), and implementable (determined by tax manager power). A large part of previous research has estimated the influence of firm characteristics, which we define as part of the business context, on the tax expense, while the other influences that we identify have largely been left "out of the equation". In order to apply and operationalize the identified three-hurdle concept, we construct five short, real-world company case studies. In these case studies, we show how variation in two key constructs across companies leads to different levels of tax expense. First, companies vary widely in the aggressiveness of their aims of tax planning. Second, tax managers can assume very different levels of power in their organization, determining the ability to implement tax planning methods. In conclusion, we provide generalizable insights into the tax planning process of companies which help to explain the observed variation in tax expenses across firms.
{"title":"The Three Hurdles of Tax Planning: How Business Context, Aims of Tax Planning, and Tax Manager Power Affect Tax Expense","authors":"Anna F. Feller, Deborah Schanz","doi":"10.2139/ssrn.2512177","DOIUrl":"https://doi.org/10.2139/ssrn.2512177","url":null,"abstract":"The question of why some companies pay more taxes than others is a widely investigated topic of interest. One of the famous suspect explanations is a phenomenon called tax avoidance. We develop a holistic theoretical concept of influences on corporate tax planning through a series of 19 in-depth German tax expert interviews. Our findings show that three distinct hurdles in the tax planning process can explain different levels of tax expense across companies. Those three hurdles are which tax planning methods are. available (defined by business context), desirable (given via aims of tax planning), and implementable (determined by tax manager power). A large part of previous research has estimated the influence of firm characteristics, which we define as part of the business context, on the tax expense, while the other influences that we identify have largely been left \"out of the equation\". In order to apply and operationalize the identified three-hurdle concept, we construct five short, real-world company case studies. In these case studies, we show how variation in two key constructs across companies leads to different levels of tax expense. First, companies vary widely in the aggressiveness of their aims of tax planning. Second, tax managers can assume very different levels of power in their organization, determining the ability to implement tax planning methods. In conclusion, we provide generalizable insights into the tax planning process of companies which help to explain the observed variation in tax expenses across firms.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"233 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72784300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A significant body of research both internationally and in New Zealand has been devoted to understanding the factors that influence compliance with tax law. Early studies on compliance were primarily focused on individuals and income tax. Recent comprehensive reviews of the literature indicate that groups of taxpayers, such as small businesses, and compliance with other tax types, such as consumption taxes, remain under-explored.To contribute to the extant literature, this preliminary study extends prior work on the compliance attitudes or behaviour of small business owners (SBOs) by focusing on their tax attitudes toward New Zealand’s goods and services tax (GST) system. In particular, their perceptions of deterrence (eg chance of being audited or penalised), tax morale, social norms (eg other business taxpayer’s compliance attitudes), perception of the tax system (eg fairness, complexity, tax burden), and tax administration (eg trust in authority) are examined.The results show some evidence of “mental accounting” which is in line with Adams and Webley’s study. Not all SBOs perceived the GST system as being reasonably simple or easy to understand. Many owners also indicated that they relied on accounting software packages for recording their GST transactions and they appeared to assume their tax practitioners would pick up any errors they make. The results further indicate that tax penalty and tax audit are salient in the minds of SBOs. The majority of SBOs always tried to file a correct and timely tax return in view of the potential cost of incurring penalties for not doing so. Although the tax system was perceived as being reasonably simple, issues relating to internet transactions and GST on imports, and the burden of compliance cost of GST were particularly frustrating to SBOs. They also had different personal experiences in their dealings with Inland Revenue and different perceptions of Inland Revenue’s fairness. The SBOs’ GST morale with regards to proper invoicing and classification of goods and services was found to be positive. The majority would not feel good in falsifying invoices or misclassifying goods or services, although some suspected others did engage in such activities. Many are also aware of customers’ preference to pay cash to business owners to avoid GST and one-third of the sampled owners even admitted doing so themselves. These insights have several implications for tax authorities.
{"title":"Small Business Owners' Attitudes Toward GST Compliance: A Preliminary Study","authors":"L. Woodward, L. Tan","doi":"10.2139/ssrn.2666317","DOIUrl":"https://doi.org/10.2139/ssrn.2666317","url":null,"abstract":"A significant body of research both internationally and in New Zealand has been devoted to understanding the factors that influence compliance with tax law. Early studies on compliance were primarily focused on individuals and income tax. Recent comprehensive reviews of the literature indicate that groups of taxpayers, such as small businesses, and compliance with other tax types, such as consumption taxes, remain under-explored.To contribute to the extant literature, this preliminary study extends prior work on the compliance attitudes or behaviour of small business owners (SBOs) by focusing on their tax attitudes toward New Zealand’s goods and services tax (GST) system. In particular, their perceptions of deterrence (eg chance of being audited or penalised), tax morale, social norms (eg other business taxpayer’s compliance attitudes), perception of the tax system (eg fairness, complexity, tax burden), and tax administration (eg trust in authority) are examined.The results show some evidence of “mental accounting” which is in line with Adams and Webley’s study. Not all SBOs perceived the GST system as being reasonably simple or easy to understand. Many owners also indicated that they relied on accounting software packages for recording their GST transactions and they appeared to assume their tax practitioners would pick up any errors they make. The results further indicate that tax penalty and tax audit are salient in the minds of SBOs. The majority of SBOs always tried to file a correct and timely tax return in view of the potential cost of incurring penalties for not doing so. Although the tax system was perceived as being reasonably simple, issues relating to internet transactions and GST on imports, and the burden of compliance cost of GST were particularly frustrating to SBOs. They also had different personal experiences in their dealings with Inland Revenue and different perceptions of Inland Revenue’s fairness. The SBOs’ GST morale with regards to proper invoicing and classification of goods and services was found to be positive. The majority would not feel good in falsifying invoices or misclassifying goods or services, although some suspected others did engage in such activities. Many are also aware of customers’ preference to pay cash to business owners to avoid GST and one-third of the sampled owners even admitted doing so themselves. These insights have several implications for tax authorities.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84347055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study the rise of shareholder right plans aimed at protecting a firm’s net operating loss carryforwards (tax benefit preservation plans). Traditional rights plans are designed to prevent hostile takeovers and have been found to entrench management at the expense of outside shareholders. Tax benefit preservation plans, however, have the potential to benefit shareholders by protecting a potentially valuable corporate asset. We find that entrenchment concerns tend to outweigh the protection of net operating loss carryforwards when firms adopt tax benefit preservation plans. Specifically, we find that abnormal returns are negative at the announcement of a new tax benefit preservation plan. However, the full impact of plan adoption on share prices is not evident until the Delaware Courts validated their use, which also had a negative impact on the firms most likely to consider adopting a plan.
{"title":"The Litigation of Tax Benefit Preservation Plans","authors":"T. Boulton, Terry D. Nixon","doi":"10.2139/SSRN.2438003","DOIUrl":"https://doi.org/10.2139/SSRN.2438003","url":null,"abstract":"We study the rise of shareholder right plans aimed at protecting a firm’s net operating loss carryforwards (tax benefit preservation plans). Traditional rights plans are designed to prevent hostile takeovers and have been found to entrench management at the expense of outside shareholders. Tax benefit preservation plans, however, have the potential to benefit shareholders by protecting a potentially valuable corporate asset. We find that entrenchment concerns tend to outweigh the protection of net operating loss carryforwards when firms adopt tax benefit preservation plans. Specifically, we find that abnormal returns are negative at the announcement of a new tax benefit preservation plan. However, the full impact of plan adoption on share prices is not evident until the Delaware Courts validated their use, which also had a negative impact on the firms most likely to consider adopting a plan.","PeriodicalId":22313,"journal":{"name":"Tax eJournal","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86031479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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