Biography emphasizing his work as a theorist from the Grove Concise Dictionary of Music entry at WQXR radio.

Biography with overview of his theoretical works and link to the Florentine Group from the Here Of A Sunday Morning radio program.

Speculation by Eleonora M. Beck concerning the relationship of the musician and the artist.

Essay with notes and sources by Margo Schulter for the Mills College Tuning Digest.

Detailed study by Jay Rahn for Music Theory Online with abstract, notes, diagrams, and RAM audio examples.

Investigation by Joe Monzo based on the Lucidarium with proposed ratios, charts and graphs.