Handbook of qualitative research / Norman K. Denzin, Yvonna S. Lincoln
Ground rules for social research: guidelines for good practice
Investigating the sosial world : the process and practice of research / Russell K. Schutt
Social science under debate : A philosophical perspective / Mario Bunge
Key concepts in social research / Geoff Payne, Judy Payne
Pene / A. Hamid Sonhadji