Wayne Stewart did a PDF conversion--not just a
scan--of
the manual for the Apple II Programmers Aid ROM. There
Someplace in my office I have a old program by Laser Systems that
reads the rom and makes a "clean" commented disassembly listing of
it. Randy Hyde wrote it as a kind of exercise for his disassembler,
so its pretty complete as I remember with proper variable names etc.
Apple didn't let it stay long on the market though.