Ellis, H., & Ellis, H. (1921). Sudies in the psychology of sex: By Ellis Havelock (3. Auflage, revised and enlarged.). Davis.

Ellis, Havelock, and Havelock Ellis. Sudies in the Psychology of Sex: By Ellis Havelock. 3. Auflage, revised and enlarged. Philadelphia: Davis, 1921.

Ellis, Havelock, and Havelock Ellis. Sudies in the Psychology of Sex: By Ellis Havelock. 3. Auflage, revised and enlarged. Davis, 1921.