1. Of course, the one 'must have' resource is the English translation of the
Muye Dobo Tong Ji, available from
Turtle Press in paperback or hardback. The MDTJ was a compiltaion of martial arts for military use in Korea, commissioned by King Junjo and completed around 1790. Based on two older Chinese references, with many added historical notes and references to other historical writings, the MDTJ gives a 'snapshot' of weapons, techniques, and stances for battlefield use. While it will not allow you to reconstruct a historical Korean sword art, it will show the overlap, similarities, and differences between Korean, Chinese, and Japanese swords and techniques at that time, and it will allow you to dispell many of the non-historical fantasies regarding Korean martial history.
2.
The Art of Zen Sword by Kim, Chang Sik - provides more a philosophy than a history. Kim was the founder of the modern Korean sword art of shimgumdo. While in meditation during a prolonged fast as a young Buddhist monk in Korea (c.1930), Kim claims to have received 100 forms in a vision, with no prior martial arts experience. He received approval from his higher-ups to teach his art as a path to 'mind-sword enlightenment', and is still alive and teaching in a Buddhist enclave near Boston, MA, USA. Shimgumdo is important because of its impact on some of the development of Haidong Gumdo, particularly the Hankuk Federation. If you are interested, watch for used copies of this book on eBay.
3.
The 'White Book' - available in Korean only, but with enough detail that a student with a modest introduction to hangul and familiarity with a few stances and techniques (and/or a friend who speaks Korean) to provide a great introduction to modern Haedong Kumdo. The 'White Book' is the official textbook of forms and techniques for the Hankuk Haedong Kumdo Federation (The second largest of the two main HDGD world federations). The Hankuk Federation has also put out a
4 - VHS video tape set that covers all the basics of the art, from basic grips, stances, techniques to forms, sparring, and cutting.
4. The rest of the references that I would suggest are all online. Do a search on this forum. (Bob, if I'm not allowed to 'name drop' other forums, please delete this next section). Then, search the history sections of Anthony Boyd's
Haidong Gumdo forum (the best single web resource I've found dedicated explicitly to haidong gumdo),
Kingdomfighter (a site primarily dedicated to Korean Kumdo (kendo), but with great historical discussion on Korean swords and swordsmanship), and
Sword Forum International.