The Actor Model in 10 Minutes (2015)

Knowing the Actor Model axioms is a start, but it doesn't get you very far. In the end you need some higher level theory of organisation, e.g. of communication patterns. I found Gul Agha's book interesting (freely available)[0]. And also stuff coming out of the Akka community, e.g. [1]

This is interesting too: Video: "Roland Kuhn - Akka Typed: Between Session Types and the Actor Model - Curry On"[2].

[0] https://dspace.mit.edu/handle/1721.1/6952

[1] https://www.manning.com/books/reactive-design-patterns

[2] https://www.youtube.com/watch?v=XyegYGzD9kM