[edwintorok]

Although not a book per-se, the tutorials on the OCaml.org site are based on the old ocaml-tutorial.org ones, which is among the ones I used to get started (there was no Real World OCaml, or OCaml from the Very Beginning at the time): http://ocaml.org/tutorials/

For future reference, all books should be listed here: http://ocaml.org/books.html