"mixed relationships of this kind can become the source of various perturbations for the physician"

 'Irma', real name Anna Hammerschlag (1861-1938), was the daughter of Freud's religious instructor at the Gymnasium (See note to page gymnasium).  A close friend of his wife Martha, she also became godmother to their youngest child Anna.

'Otto' stands for Austrian pediatrician Oskar Rie (1863-1931), a close friend and occasional collaborator of Freud's from the beginning of his career until the end of his life.  Brother-in-law to his sometime rival for Freud's affections, Wilhelm Fliess (See note to page 93). 

 'Leopold' has been identified as Ludwig Rosenberg (1862-1928) - another pediatrician colleague of Freud's during the early stage of his career, and another brother-in-law to Oskar Rie (above). 

'Dr M' is Josef Breuer, Freud's sometime mentor whose collaboration with him had resulted in their joint publication of Studies in Hysteria (1895), now seen as the founding text of psychoanalysis (See note to page 80).