FM Theory and Applications By Dr John Chowning and David Bristow https://www.burnkit2600.com/manuals/fm_theory_and_applications.pdf https://www.burnkit2600.com/

FM Theory and Applications By Dr John Chowning and David Bristow https://www.burnkit2600.com/manuals/fm_theory_and_applications.pdf https://www.burnkit2600.com/manuals/fm_theory_and_applicatio... Mostly focused on FM as applied by the DX7 IIRC. But really good overview of how FM works since it's the guy who invented it.