Other
The Equal Tempered Scale & Peculiarities of Piano Tuning
The author offers a complete explanation of the physics behind piano tuning and why piano tuning is an intricate process. Illustrations and graphs are included.
OpenStax
Open Stax: Catherine Schmidt Jones: Pitch Sharp, Flat and Natural Notes
Learn about the meanings and uses of pitch and accidentals. Including sharp, flat, natural and double sharps and flats, this lesson explains why they are necessary.