I just want to share an article I found about the works of Gassan Sadakazu. You can download the article here.   https://www.metmuseum.org/art/metpublications/A_Study_of_the_Works_of_Gassan_Sadakazu_The_Metropolitan_Museum_Journal_v_5_1972?Tag=Weapons&title=&author=&pt=0&tc=0&dept=0&fmt=0   Best regards, Ed