Focus groups
MLA
Krueger, Richard A, and Mary Anne Casey. Focus Groups : a Practical Guide for Applied Research. 5th edition. Thousand Oaks, CA: Sage, 2015.
APA
Krueger, R. A, & Casey, M. Anne. (2015). Focus groups : a practical guide for applied research. 5th edition. Thousand Oaks, CA: Sage.
Chicago
Krueger, Richard A., and Mary Anne Casey. Focus Groups: A Practical Guide for Applied Research. 5th edition. Thousand Oaks, CA: Sage, 2015.