For a unique vision of Okinawa's past I'd suggest Itosu and his students books.
On my blog http://isshin-concentration.blogspot.com/
I've been exploring them a bit.
April 2010 - Itosu Anko - New Direction for Toudi
May 2010 - Itosu's reflections - (e posts)
"The Game is Afoot Watson"
"Watson, Look for the smallest detail"
"It's not BUNK...I say Watson"
Doing research into Itosu's letter to the Okinawa school committee I realized most of the books published in the 20's and 30's in Japan were from his students, and they really cross refrence themselves to some extent.
My blog has just touched on a few high points you may find interesting.
Here are a few of the books involved ( and remember it was Itosu's copy of the Bubishi that inspired Funakoshi and Mabuni to reveal it's existence).
P.McCarthy (though I recommend the latest edition where I add to the introductions)
and of course both F.Ginchin and K. Mabuni sharings
Ryuku Kenpo Karate (Karate Jutsu)
Karate Do Kyohan
1934 – Univ of Hawaii collection)
1973 – trans. T. OShima
Karate-Do Nyumon 1099 Trans. J. Teramoto
Motoobu Choki to Ryukyu Karate
Reprints of Okinawn Kenpo Toudi Jutsu Kumite-Hen
Watashi no Kaate Jutsu (My Art Karate)
Motobu Choki Karate My Art trams. P McCarthy
Mutsu Zuiho (originally a student of Funakoshi)
Karate (Toudi) Kempo - one of the true gems though only in Japanese.
Kobu Jizai Goshinjutsu Karate Kempo trans. M. McKenna
Seipai no Kenkyu (the Study of Seipai) Kobo Jizai (Attack and Defense at Will)
Appendix – Bubishi
Sepai no Kenkyu Kobo Jizai Karate Kempo trans. M. McKenna
Karatedo Taikan (reprint 1991)
English Trans. McMcKenna This last is an incredible treasure.