@techreport{oai:kobe-cufs.repo.nii.ac.jp:00001214,
 author = {Tanaka, Satoru},
 issue = {28},
 month = {Mar},
 note = {Patent pool may be the solution for dissolving the economic inefficiencies caused by the existence of the patent thicket. In order to determine whether this is the case or not, the index that clarifies the existence of the patent thicket is necessary. In this paper, using the simple index (which Clarkson (2005) proposed) focused on the citation relationship of the patent network, I examine whether there exists patent thicket over the patent space surrounding Japanese ARIB patent pool. On the country of Clarkson’s results, the density of citation in the pooled patent intra-network is thinner than that in the patent space surrounding the pool. However, through focusing on the relationship between pooled patents and their “hull”, it is verified that there exists patent thicket over the ARIB patent pool., 文部科学省科学研究費（基盤研究(A)）2007年度～2009年度、研究課題番号：19203015、代表者：土井教之, application/pdf},
 title = {Toward the patent thicket detection : an empirical study on Japanese ARIB patent pool},
 year = {2008}
}