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It actually might be the evening when you see Linda's book now that I'm thinking about it.You can only click on the book in Linda's room in the afternoon after you see her reading it during a coital spy session.
On an unrelated note (a few people were asking about it earlier) if you want to access the hidden room in Bob's office, you need to get the book out of his car using the keys by the red panther statue. Go back to the office in the afternoon when Bob is gone and put that book on the bottom shelf of the book shelf in the far corner. That Bob is a kinky feller.