Note 2 — Chapter I · —INTRODUCTION.
Reading edition
The chief general collection of data (not here drawn upon) concerning homosexuality among animals is by the zoölogist Prof. Karsch, "Päderastie und Tribadie bei den Tieren," Jahrbuch für sexuelle Zwischenstufen, vol. ii. Brehm's Tierleben also contains many examples. See also a short chapter (ch. xxix) in Hirschfeld's Homosexualität.