The red volume on Ullman’s desk appears to be the Hotel & Motel Red Book, a hotel directory. The connection to Jung is an interpretive parallel, not a verified identification of the prop.
Jung’s Red Book records his psychological observations and experiments on himself. The parallels with Jack’s isolation, writing, and apparent loss of touch with reality offer a way to read the scene. Jung’s manuscript was first published in 2009.
In this image · No.5
The red book on Ullman’s desk; the Jung connection is interpretive.