Compare that to the entire bookcases that have been written about Java, .NET, Visual Basic, etc.
* Erlang is not as popular.
* It is rather a niche language suited for some domains but it is not for others (compute oriented languages). So not many "How to write games in Erlang" or "Statistics in Erlang"
* Erlang documentation is pretty good. It is not pretty (look like it its style got stuck in late 90s), but it is comprehensive
* Erlang programmers I find are good self-starters and of higher quality than other programmers. It is just what I observed I maybe wrong. This is the same as Haskell or Rust perhaps. That means they learn and find out stuff on their own.
* Erlang is self-consistent. There are not that many ways to do one thing. Not like Scala, C++ or Java. That means there is usually a canonical good way. That also means less "Erlang patterns". Usually large number of "patterns in X" means there is some deficiency in the language or library. That means a small cottage industry of writing "patterns in X" books.