I’ve got lots of books, 50+, dunno which one is the best. Yet if I was to buy a good starter book that would be a long lasting quick reference of basic to advanced techniques, for all but azalea bonsai. I’d recommend it would be:
Understanding Bonsai by Pieter Loubser. He actually wrote two. The one I have is 1993 version. It’s running about $32 on Amazon. It’s comprehensive and covers a multitude of techniques succinctl, some not seen together in one book.
For azaleas there isn’t a really one good overall book imho, even the very newest ones leave something to be desired to give one a good handle on these trees. Yet there are a couple I highly recommend together for folks starting off for the first 1 - 4 years. These are:
Floral Treasures of Japan by Alexander Kennedy a good basic book. It’s on Amazon for about $25. (Last year and a half there was a shortage of available copies and the price jacked up to $125 +…. No longer!
…and Satsuki Bonsai by Janine Droste. About $40. Lots of photos, writing is spare and to the point.
cheers
DSD sends