The book "Psychopathy sexualis: With special reference to the opposite sexual instinct. A medico-legal study" by Richard von Krafft-Ebing is one of the first and quite important scientific works in the field of sexology and psychiatry. The book explores a variety of sexual abnormalities and disorders, including the differences between sexual orientations that can occur in humans. The author analyzes in detail deviations in sexual behavior and draws conclusions from a medico-legal point of view. This book became a classic source for further research in the field of sexology and the understanding of mental disorders.