Source Book of Proposed Music Notation Reforms – by Gardner Read (1987)
“A New Twelve-Tone Notation” Part VII, #18 of Style and Idea: Selected Writings – by Arnold Schoenberg (1924)
See our More Notation Systems page for links to the websites of particular alternative music notation systems.
See the Isomorphic Instruments page for links to instrument websites.
The links below are to other sites of general interest:
Music Notation Reference Guide Basic info on different elements of traditional notation.
Notational Engineering Laboratory, (broken link) a research project dedicated to studying and engineering a wide variety of notation systems in general.