This is the book I used when I was writing serial drivers for Apple II ProDOS: https://archive.org/details/6502_Assembly_Language_Programmi...

And I have a vague memory of this book: https://archive.org/details/aiimp/mode/2up

Not sure what level you're at, but I can't remember if this is the text Jef Raskin wrote, but it's a decent backgrounder: https://archive.org/details/aiirm/mode/2up