Linked from
The 11 pages that link to Pitch class, each with the reason it gives.
Pitch (music)Broader topic: It retains a note’s identity while discarding its specific register.
Musical scaleRelated: Scales usually select pitch classes, even when they span several registers.
Chromatic scaleRelated: The scale contains all twelve pitch classes in the octave.
Tone rowNarrower topic: A tone row orders pitch classes rather than fixing a single register.