When I learned Ada, I used the wikibook [1] and bought an inexpensive used textbook from Amazon. I have a basic competency of the language, and really like the quality of the compiler toolset, the type system, the "DIY" OOP (as I call it), and the packaging system. My biggest issues with it are that bindings for databases, graphics libs, and web development libs are few and far between and usually just a lonely github repo. But, as another positive, writing bindings to C libs seems pretty easy [2], so someday I'll give it a try.