↑Yoshitoshi's Women: The Woodblock-print Series Fūzoku Sanjūnisō,1995, John Stevenson. The book mentions the tradition as Chungonghua, or spring palace pictures.
↑The humor and technology of sex, 1970, Paul Tabori, page 302. Mentions the tradition as "spring palace pictures" started some time from the Song dynasty.
↑Shunga:Ten Questions and Answers,2013, page 13, by Monta Hayakawa mentions the tradition as "Chungongmihua"