Do you REALLY want me to go grab my book?
Okay...went and pulled the book. The movie came out in 1968 and the book was published in.....1968! It also states very clearly, that it is based on the screen play by Kubrick and Clarke! It was NOT after the movie came out, but concurrently.
I said it was based on the screenplay, did I not?
That was the whole point.
The book was not released until AFTER the film came out.
Same year,different release dates.
.