English literature on Turkish Classical Music Theory

I am new here, and I see that there has been an intense debate going
on on this matter, for which I don't yet qualify for participating in.
I have half a year ago started to study the ney (btw. the most
complicated instrument I ever studied), and I am interested to expand
my theoretical background on classical Ottoman music. My problem is
that my mother tongue is German, and the only other language which I
speak is English. The few German books on the subject leave the more
dry stuff like Pythagorean ratios and 53-comma-scales aside to not
bore the reader, but they are exactly what interests me. So what I
need is a source that outlines to me the theories of al-Farabi,
Urmevi, Karadeniz, Esgi, Yekta, Arel, Oransay, just to name the ones
that interest me most, and in English. Any pointer is welcome.
Thanks,
Michael