You know a film is a classic when someone write an entire book about that movie. Think of books on Citizen Kane, Gone With the Wind and Casablanca.
But no film has had more books written about it than Psycho.
Back in 1990 Stephen Rebello published Alfred Hitchcock and the Making of Psycho. Then one of the stars of the movie got into the act when Janet Leigh (and Christopher Nickens) came out with Psycho: Behind the Scenes of the Classic Thriller in 1995.
Then the floodgates opened. There were 7 more tomes between 2001 and 2010. Then in 2013 a book of 21st Century essays on the film.
Oh, that shower scene.