Master Donggao's 東皋 music notes have been a subject of academic studies since Robert van Gulik discovered him in the 1940s. Prof. Li Meiyan 李美燕 in Taiwan is an expert in this area. I found one of her articles online and there are many more.
李美燕，〈東皋心越之琴道及其自創琴歌研究〉。《藝術評論》，21期，2011年
李美燕，〈高羅佩與東皋琴學—以《明末義僧東皋禪師集刊》與《東皋琴譜》為考察對象〉，《琴學薈萃—第二屆古琴國際學術研討會論文集》。濟南：齊魯書社，2011年。
