Books or papers going into detail about Schoenberg and Cage?

Hello everyone,

I was wondering if anyone knows of any books or papers that go into
critical detail concerning Cage's relationship with Schoenberg. We
have Cage's words and anecdotes but I haven't yet found a critical
analysis of their relationship.

Like what did Schoenberg really think of Cage. Or what were
Schoenberg's classes at USC and UCLA really like (interviews with
other students?).

Thanks,
Dave Bellows