Changes

The vast majority of papers use the GIM index or some subset of the items in the GIM index. Each index is constructed using the Investor Responsibility Research Center data from ''Corporate Takeover Defenses'' Rosenbaum 1990, 1993, 1995, 1998, 2000, 2002. I can only locate physical copies of these books, so I believe assume research assistants put together databases by hand using those physical copies.  In order to obtain this data, I would contact the authors of the more recent papers or the IRRC at http://irrcinstitute.org/contact/.