Boulanger - "The Csound Book" (another classic language I still use today)
Greenbaum and Barzel - "Audio Anecdotes". A fascinating series of 3 volumes with all sorts of wisdom on FX design, studio systems and composition
Wilson, Cottle and Collins - "The Supercollider Book". In the style of The Csound Book, but with SC.
Loy - "Musicmathics". A rare and much under-rated two volume set on the equations behind audio DSP
Bilbao - "Numerical Sound Synthesis". A hard but rewarding journey to understanding audio physics as linear diff systems and implementing them efficiently in C, Goes well with Perry Cook's stuff.
Benson - "Music a mathematical offering" Very unusual book that analyses many subjects in music physics. Equations but no code.
Miranda "Computer Sound Design". More about music synthesis than "sound design" imho, but has some interesting fringe methods like cellular autonoma and genetic algorithms.
[0] https://mitpress.mit.edu/books/audio-programming-book
Edit: My goal is to make a mini-synth which takes input from the computer keyboard.
The Computer Music Tutorial by Curtis Roads is a good companion here if you want inner workings. You might be able to snag a PDF copy online to see if it's for you.
Audio Programming Book is entirely in C and can be a bit of a pain to get things working in C if you're new to programming (although highly worth the initial struggle if you're looking at it with a career in mind), although I'd still recommend stepping from Max/MSP into MATLAB/Python, which focuses on functionality rather than programming itself.
Python is also bit more beginner friendly, although C++ will probably end up being your long term bet.
I'd pick up the Pyo library for python, and/or a tutorial like this one, after dabbling with Max/MSP a bit: https://python.plainenglish.io/build-your-own-python-synthes...
Then if you want to get even deeper into the DSP, you could go with pretty much any of the other resources the others have mentioned here. My personal faves are the Steven Smith DSP book, Julius Smith's resources (with its runnable MATLAB scripts), and DAFX book by Udo Zolzer.
It gives a concise explanation for the techniques and theories for signal processing while showing practical code examples.
[2] https://msp.ucsd.edu/techniques.htm
[3] https://mitpress.mit.edu/9780262014465/the-audio-programming...