The Sigmund Freud Complete Works (SFG), established in 2015 by Christfried Tögel, consists of 23 volumes and is the first collection of writings that includes all works intended for publication by Sigmund Freud—this includes his reviews and contributions to manuals and encyclopedias. Freud's writings are presented in the form in which they were first published. Each text is preceded by a brief introduction that provides context regarding the biographical and historical background. An overview at the end of each volume makes it easier to locate the texts within the collected writings, the complete works, and the study edition. The three essays on sexual theory represent one of the most important works in volume 10, where Freud introduces the concept of drive for the first time. This volume also includes the "Fragment of a Hysteria Analysis," the "Dora Case," which served as the basis for his theories.