- Japanese: 甲陽軍鑑 (Kouyougunkan)
The Koyo Gunkan is a history of the Takeda clan of Kai province from the birth of Takeda Shingen to the death of his son Katsuyori. A substantial part of the Kôyô Gunkan is a treatise on military tactics and administrative affairs. The original consisted of 20 scrolls. It is believed to have been written by Kosaka Masanobu, a general of Takeda Shingen and later, Takeda Katsuyori.
- Kôyô Gunkan. (Edited by Yoshida Toyo), 19th edition, Tokyo, August 2005.