These tutorials by Robert Danny Davis are a wonderful opportunity to gain inspiration and knowledge about music harmony, theory and composition. Be prepared to learn outside the box of the standard course for harmony, theory.
But the standard textbooks can also be inspirational.
Surprisingly, the first few chapters of this book are evocative and inspire the imagination.
Harmony and Voice Leading (4th Edition) by Allen Cadwallader, Edward Aldwell, 978-0495189756
Laitz emphasizes the importance of Counterpoint for understanding Harmony.
The Complete Musician: An Integrated Approach to Tonal Theory, Analysis, and Listening 2nd Edition 978-0195301083, by Steven G. Laitz, Adler, the Study of Orchestration, 978-0393600520
Music for practicing piano skills.
Piano Literature by Jane Bastien, Volume 2; Volume 3; Volume-4, Volume-5,
Regards
Ray