You can't just look at the instruction set to program a powerful chip like the 6809; you've got to know more. In this book you will find all the information you need to get the 6809 working for you.
Still have my paperback copy and recently restored my nearly 40-year-old 6809 single-board computer ("Flexi Plus" by "The Computerist" of Chelmsford, Ma) so I find myself delving back into this sentimental favourite.