Great talk @dewetblomerus - I don’t think I’ve seen a talk on onboarding new team members before and I think this is well worth a watch for anyone responsible for doing that as well as for those new team members themselves 
Must admit I’ve never paid much attention to the skill level scale on books and when you mentioned that Programming Elixir was aimed at experts I thought “Waat, did I really read a programming book aimed at experts and understand it!?” but then checked the website and it looks like it’s aimed at people from mid to expert (definitely class myself as more of mid than expert, haha!) Personally I think Programming Elixir and Elixir in Action are very accessible to anyone who knows at least one programming language, especially if read together as I did… plus it’s a lot cheaper than a $6,000 course 
I too also highly recommend Learn Functional Programming With Elixir and agree it should be read after learning the basic of Elixir, whether via the docs or the aforementioned books - here’s my review of it if anyone’s interested 
