Design unclear or unknown

Johnson, R. T., University of Hawaii at Manoa, & Center for Youth Research. (1995). Parents as First Teachers: Final evaluation. State of Hawai`i, Department of Health, Healthy Start Program. Honolulu: Social Science Research Institute, Center for Youth Research, University of Hawaii.

Bartik, T. J. (2009). How policymakers should deal with the delayed benefits of early childhood programs. Unpublished manuscript.
Bartik, T. J. (2009). How policymakers should deal with the delayed benefits of early childhood programs. Unpublished manuscript.

Affonso, D. D., & Doran, D. (2002). Cultivating discoveries in patient safety research: A framework. International Nursing Perspectives, 2(1), 33–47.

Lutzker, J. R. (2006). Preventing violence research and evidence-based intervention strategies. Washington, D.C: American Psychological Association.

Dangel, R. F., & Polster, R. A. (1984). Parent training : Foundations of research and practice. New York: Guilford Press.

Parents as Teachers National Center. The early history of Missouri's Parents as Teachers program, 1981-89. (1989). (Report 89-3). St. Louis, MO: University of Missouri at St. Louis.
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Pihama, L. (1993). Tungia te ururua, kia tupu whakaritorito te tupu o te harakeke : A critical analysis of Parents as First Teachers. Thesis submitted in partial fulfilment of the requirements for the degree of Master of Arts in Education. University of Auckland.
Macklin, S. (2006). Parents as First Teachers: The foundation for success. St. Paul: Concordia University.