Forschungen über das Räthsel der mannmännlichen Liebe (The riddle of Male-Male Love) is a series of 12 pamphlets published between 1864-1870 on sexology. Ulrichs states that there are several types of men, who are differentiated in type based on sexual preference for men (Urnings) or women and masculine or feminine behaviors, such as Manning (masculine) and Weibling (feminine). Symonds references Ulrichs in both his Memoirs and A Problem in Modern Ethics, and Ulrichs' theory of Urnings infuenced Symonds' own thinking about sexual inversion.

Das konträre Geschlechtsgefühl (The Contrary Sense of Sex) is the first edition of Sexual Inversion, published in Germany in 1896.  This edition places Symonds's A Problem in Greek Ethics (Die Homosexualität in Griechenland) as the third chapter in the book. Greek Ethics is Symonds's study of "Greek love" or Greek practices of male pederasty. However, Symonds is incorrectly referred to as "G.A. Symonds" in this edition.

Sexual Inversion was published in English in 1897, a year after the German publication. This edition was suppressed by Horatio Brown, executor of Symonds's estate, by orders of Symonds's widow, and many copies were destroyed. This edition of Inversion was involved in the Bedborough trial, and was banned as an obscene text in Britain. A Problem in Greek Ethics is also notably moved to the appendix.