DELLA PORTA, Donatella, KEATING Michael (eds). Approaches and Methodologies in the Social Science: A pluralist Perspective. Cambridge: Cambridge University Press, 2008. 365 p. ISBN 978-0-521-70966-8 .
DePOY, Elizabeth and Laura N. GITLIN. Introduction to Research - Understanding and Applying Multiple Strategies. Elsevier. 2016. 398 p. ISBN 978-0-323-26171-5 .
PUNCH, Keith. Introduction to Social Research: Quantitative and Qualitative Approaches. 2nd edition. London: Sage, 2005. 320 p. ISBN 0-7619-4417-6 .