The Just intonation Primer by David B. Doty
On The Sensations of Tone. Hermann Helmholtz
Genesis of a Music by Harry Partch
Divisions of the Tetrachord by John Chalmers
Microtonality and the Tuning Systems of Erv Wilson by Terumi Narushima (available in Octotober 2017)
Musical Mathematics by Cris Forster
Harmonic Experience by W. A. Mathieu
'Temperament' and 'Temperament; or the Divisions of the Octave' R.H.M. Bosanquet
Greek Musical Writings: Volume II, Harmonic and Acoustic Theory. Edited by Andrew Barker.
Multiple Division of the Octave and the Tonal Resources of 19-Tone Temperament. Mayer Joel Mandelbaum. Thesis
The Greek Aulos by Kathleen Schlesinger
Augusto Novaro Musica Natural and approximation (Two editions) 1927-29 and 1951
Tuning and Temperament: a Historical Survey. Barbour, J.Murray 1951
Bach and Tuning. Johnny Reinhard 2016.
Harmonics and Spirals. Neil Haverstick. 2016 https://microstick.net/product/harmonics-spirals/
This list also covers much of a Just Intonation nature that best is seen there as opposed to copying.
I will be updating this as i am sure i am forgetting many