Seconded. Motion carried.
Oh, and while I'm here, there are some to avoid as well (this gets contentious, as personal biases come into it, probably more than in recommendations!). Personally, I'd avoid most stuff by Stephen Turnbull, especially anything he has to say on "ninja", he tends to look at everything with very Western eyes, and it colours his interpretation of everything, leading to some rather inaccurate accounts and theories. Serge Mol has a few books out (Classical Fighting Arts of Japan, Classical Weaponry of Japan, Classical Swordsmanship of Japan) that are very interesting, but flawed in a few ways. So they would be recommended later, when you know what you're looking at a bit more. Oh, and things like Samurai Fighting Arts by Tanaka Fumon, again interesting, but not really a recommendation for a number of reasons. Pretty pictures, though!
For another good one, in the late 70's there was a documentary series on the BBC called Way of the Warrior. It covered a whole range of arts, from a number of different countries, and included Katori Shinto Ryu when looking at Japanese Swordsmanship (it also covered Karate, Aikido, Naginatado, and lots more [non-Japanese] arts as well). If you can find the documentary itself (I think it's in pieces on you-tube), that is great, there's also a book companion to it which is still in print.