The Language and Materials of Music Third Edition
by Kendall Durelle Briggs
For a deep-dive into Common Practice music theory, this book is for you!
Mark Sarnecki Music Theory, Second Edition
by Mark Sarnecki et al.
Comprehensive coverage in three levels for late-elementary or early-intermediate students.
Celebrate Theory - The Royal Conservatory - Preparatory - Level 10
by The Royal Conservatory
Preparatory to advanced, The Royal Conservatory's progressive 10 level series provides workbooks and online materials.