its an interesting and forgotten area maybe everything darkened because of the damned long years of war in indochine
if you dont had see this I stumple also about this theme http://forums.nitroexpress.com/showflat.php?Cat=0&Number=218490&an=0&page=0#Post218490

problem is that most of the books are only available in french. one have to found a publishing house and make good quality but affordable english editions for the international armchair hunter.