I really like Harry Cook's work, I think it may be the best available work on Shotokan history (but hey what do I know?), but I'm not sure he's the last word in all karate history.
In fact the Okinawan seniors are working on their own Encyclopedia of Karate and whenever it is done, it will be the definitive work on Okinawa's arts. It will be interesting to see what they share for there are so many different Okinawan arts, likely every dojo is one in reality.
Most telling are the books published in the 1930's that are slowly being translated into English and hopefully will be eventually shared. Works like Mutsu's Karate Kempo which seems to have been the template for the later JKA Shotokan curricula. More so as 1/2 of Mutsu's work shows Karate applications, fun things like bobbing, weaving, grappling counters, so much that people are unaware of today but was clearly shown in 1933.
Perhaps Mabuni Kenwa's works on the Goju Kata Sanchin, Seiunchin and Seiipai as well as sharing a portion of the Bubishi with the reading martial public. Of ocurse Mabuni can be found in any number of other works in that decade, really working to share Karate's existence.
Or Funkaoshi's original 'Karate Do Koyan'. Or many other telling works like Nakasone's 'Encyclopedia of Karate' and more. Together they show what those Okinawan's wanted to show and are a clear record of what Karate represents than just a history text, as far as any book can go.
pleasantly,