Levin, M.1999. “Action research paradigms”. In D. J. Greenwood (ed.), Action Research – From practice to writing in an international action research development program. Amsterdam/Philadelphia: John Benjamins. pp. 25–37.
Liu, M.1991. “Grondbeginselen van actie-onderzoek”. (Fundamentals of action research) Gedrag en Organisatie, 4(4): 239–257.