The community of toki pona speakers has grown to the point where there is no such thing as an authoritative source, much like a natural language. If you want to

The community of toki pona speakers has grown to the point where there is no such thing as an authoritative source, much like a natural language. If you want to learn in depth your only option is to join a chatroom and talk to people. For intro material, there are many free options beyond the official book. https://devurandom.xyz/tokipona/ https://devurandom.xyz/tokipona/ is quite good.