The Just intonation Primer by David B. Doty
http://www.dbdoty.com/Words/Primer1.html
On The Sensations of Tone. Hermann Helmholtz
http://store.doverpublications.com/0486607534.html
Genesis of a Music by Harry Partch
https://monoskop.org/images/b/be/Partch_Harry_Genesis_of_a_Music_2nd_ed.pdf
Divisions of the Tetrachord by John Chalmers
http://eamusic.dartmouth.edu/~larry/published_articles/divisions_of_the_tetrachord/
Microtonality and the Tuning Systems of Erv Wilson by Terumi Narushima (available in Octotober 2017)
https://www.routledge.com/Microtonality-and-the-Tuning-Systems-of-Erv-Wilson/Narushima/p/book/9781138857568
Musical Mathematics by Cris Forster
https://www.amazon.com/Musical-Mathematics-Science-Acoustic-Instruments/dp/0811874079
Harmonic Experience by W. A. Mathieu
https://www.amazon.com/Harmonic-Experience-Harmony-Natural-Expression/dp/0892815604
'Temperament' and 'Temperament; or the Divisions of the Octave' R.H.M. Bosanquet
http://anaphoria.com/library.html
Greek Musical Writings: Volume II, Harmonic and Acoustic Theory. Edited by Andrew Barker.
https://www.amazon.co.uk/Greek-Musical-Writings-Cambridge-Literature/dp/0521616972
Multiple Division of the Octave and the Tonal Resources of 19-Tone Temperament. Mayer Joel Mandelbaum. Thesis
http://anaphoria.com/mandelbaumthesis.pdf
The Greek Aulos by Kathleen Schlesinger
https://archive.org/details/KathleenSchlesingerTheGreekAulos
Augusto Novaro Musica Natural and approximation (Two editions) 1927-29 and 1951
http://anaphoria.com/novaro.html
Bach and Tuning. Johnny Reinhard 2016.
https://www.amazon.com/Quellen-Studien-Musikgeschichte-Gegenwart-Antiquity/dp/3631672055?fbclid=IwAR3yAvoq3AzNXlG8zVEto7fjXDm-Yb-BPPp29VpCLjHQcsHdvZrnIbiIOTo
Harmonics and Spirals. Neil Haverstick. 2016 https://microstick.net/product/harmonics-spirals/
A Theory of Evolving Tonality- Yasser
I will be updating this as i am sure i am forgetting many
