Braut, Christian The Musician's Guide To MIDI : SYBEX Braut Christian : Free Download, Borrow, and Streaming : Internet Archive
lemmy.ca
Many books prior and since claim to be authoritative, but this book is truly the best reference for MIDI, giving a friendly introduction and then a deep dive...

Best book for learning the ins and outs of MIDI I’ve ever encountered. Relatively obscure, but an invaluable reference book for anyone wanting to dig into the details of how MIDI works.