Porter, J., & Lacey, P. (2005). Researching learning difficulties: A guide for practitioners. P.C.P. ; SAGE Publications.

Porter, Jill, and Penny Lacey. Researching Learning Difficulties: A Guide for Practitioners. London : Thousand Oaks, CA: P.C.P. ; SAGE Publications, 2005.

Porter, Jill, and Penny Lacey. Researching Learning Difficulties: A Guide for Practitioners. P.C.P. ; SAGE Publications, 2005.