After that, I would recommend the new (beta) version of Real World OCaml — it gets a lot more in depth about more advanced language features: https://dev.realworldocaml.org/toc.html
There is also https://www.cs.cornell.edu/courses/cs3110/2019fa/textbook/. Yours is 2019 Spring, this is 2019 Fall. This version covers many more topics. Might be useful for some. :)
Just to add more:
- https://caml.inria.fr/pub/docs/u3-ocaml/ocaml.pdf (Using, Understanding, and Unraveling The OCaml Language by Didier Rémy)
- https://ocaml.github.io/ocamlunix/ocamlunix.pdf (Unix System Programming in OCaml by Xavier Leroy and Didier Rémy)
- https://caml.inria.fr/pub/distrib/ocaml-4.12/ocaml-4.12-refm...
- https://ocaml.org/learn/tutorials
You might also find interesting stuff here: https://blog.janestreet.com/. There are videos, too: https://blog.janestreet.com/why-ocaml/
After that, I would recommend the new (beta) version of Real World OCaml — it gets a lot more in depth about more advanced language features: https://dev.realworldocaml.org/toc.html