I went online looking for the author of a book I saw someone reading on the subway, called The Challenge of Fate. It turned out to be an out of print book by a German writer but my search led me to this amazing website that will connect a writer with other writers:
I chose William Faulkner because the main character of my new book read him in college. I went on this site and got a real insight into how my character reads. I am always teaching the importance of knowing your characters frame of reference, and to be able to instantly gain a possible chain of writers and as a result to have a map of the characters reading history seems like a great tool.
As an exercise:
Decide the most influential book your main character has read at any age and use this website to see the connections. Pick one book by one of the connected authors and write a short book report or essay as if you were the main character.