If you read 1L, then you should remember that one character in the book studied hornbooks for each subject the summer before law school. I don't think this is necessary, but if you feel compelled the books below are available through online legal book sellers.
Hornbooks are universal, and will work with any professor. In each subject there is usually one or two hornbooks that professors and students recognize as the best. An example is Prosser on Torts. Every single first year should and most likely will own this book. It is the recognized authority on the black letter law of Torts.
There are a lot of Hornbooks out there. Here are my favorites: