https://www.militaria.co.za/nmb/topic/53846-book-co-authored-by-nakata-kanehide-on-making-kogatana/
Book co-authored by Nakata Kanehide on making kogatana - Wanted to Buy - Nihonto Message Board
It sells for about 50 bucks in Japan, if you can find it. Please let me know if you have a copy you would be willing to sell. John C.