大家有没有什么比较好的专利引用数据来源？

我是一名在校研究生，主要研究企业专利战略与专利联盟相关问题，但是在做实证分析时，面临专利引用数据来源的限制，请教大家有没有什么比较好的数据来源，方便、质量好且最好不收费。谢谢大家

USPTO
什么叫做实证分析啊？

专利引用数据？
怎么个意思？
不是很清楚你的意思
如果是专利信息的话，国知局，欧专局这些都可以啊，也都是免费的
现在有很多搜索引擎也在提供这些信息了

OECD patent databases

http://www.oecd.org/document/41/0,3343,en_2649_34451_40813225_1_1_1_1,00.html#rawdata

The OECD has developed 3 different sets of patent data, for research and analytical work only.  The detailed raw data can be downloaded from a secure – password protected – server. Please send an e-mail to sti.contact@oecd.org to request access to the data, mentioning \"OECD patent database\" in the title of your message.

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      OECD Triadic Patent Families Database, October 2008: set of patents filed for at the EPO, the Japan Patent Office (JPO) and granted by the USPTO that share one or more priority applications.
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      OECD REGPAT Database, January 2009: patent applications to the EPO and PCT filings linked to regions using the inventors/applicants addresses.
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      OECD Citations Database, 2006: citations from patents published by the EPO and the WIPO (PCT).

The NBER U.S. Patent Citations Data File: Lessons, Insights, and Methodological Tools

http://www.nber.org/patents/