Sigmund Freud 
Three Contributions to the Theory of Sex 

Landmark study examines sexual aberrations, infantile sexuality and the transformations of puberty. A unique work, according to translator A. A. Brill, it is "unlike other works on sex…of interest not only to the student of abnormal manifestations [but also] indispensable to the psychologist, the anthropologist, sociologist, the jurist, and above all the teacher."