The book titled "Kohitsugire meyasu" which was said to be written by an disciple of Ryosa, Ryoin FUJIMOTO (Kizan KASAHARA), is valuable because it described a method of appraisal of old writings.
了佐の弟子、藤本了因（笠原箕山）が著したとされる『古筆切目安』という本は、古筆鑑定に1つの方法論を述べた点で価値が高い。