The legal struggle between the publishing industry and Google over Google Book Search took a chilling turn yesterday as Yahoo refused Google’s request for info on how it copies books digitally. As the Associated Press notes, Amazon.com gave Google a similarly cold shoulder last month, puncturing Google’s plans to defend itself against charges of copyright infringement by comparing “its plans to provide online access to millions of library books” to “similar projects involving some of its biggest rivals.” As far as Yahoo’s concerned, that’s just an excuse to try to get hold of its trade secrets, and they aren’t falling for it.