Final answer:
Sigmund Freud's work in developing psychoanalysis was significantly influenced by Carl Jung, Alfred Adler, Anna Freud, and Karen Horney.
Step-by-step explanation:
Sigmund Freud's work in developing psychoanalysis was significantly influenced by a) Carl Jung and Alfred Adler, and b) Anna Freud and Karen Horney. Freud attracted many followers who modified his ideas to create new theories about personality, known as neo-Freudians. Four notable neo-Freudians include Alfred Adler, Erik Erikson, Carl Jung, and Karen Horney.