@book{Spitz, author = {Spitz, Ren{\´e} A.}, title = {Nein und Ja, Stuttgart (Ernst Klett Verlag) 1957.}, language = {de} } @book{Spitz, author = {Spitz, Ren{\´e} A.}, title = {The first year of life. A Psychoanalytic Study of Normal and Deviant Development of Object Relations, New York (International Universities Press) 1965.}, language = {en} }