„The research needed for social practice can best be characterized as research for social management or social engineering. It is a type of action research, a comparative research of the conditions and effects of various forms of social action, and research leading to social action. Research that produces nothing but books will not suffice.“
— Kurt Lewin German-American psychologist 1890 - 1947
Quelle: 1940s, Action research and minority problems, 1946, p. 35.