This context comes from a part of Stephen King's book "The Shining" in which Wendy, Jack's wife, speaks to him about Danny, their son. She thinks Danny isn't eating enough lately and spending too much time trying to teach himself how to read (which she thinks is to please them). The following text is Jack's answer to this claim.
"They taper off" he said vaguely. "I think I read that in Spock. He'll be using two forks again by the time he's seven."
Spock was the first pediatrician to study psychoanalysis to try to understand children's needs and family dynamics
The phrase "I read that in Spock" is weird to me. I wouldn't say I read that in King or Dostoevsky. I would say "I read that in one of the King's books or Dostoevsky's". Initially I thought it might be a magazine named after him, in which case the sentence would make perfect sense. Also, there are no books of his titled with his name only. Is this a mistake, informal speech, or some kind of linguistic invention of King's, for which he's known, after all?