Sommer, R. (1997). A practical guide to behavioral research: Tools and techniques (4th ed.). OUP.
Cita Chicago (17th ed.)Sommer, Robert. A Practical Guide to Behavioral Research: Tools and Techniques. 4th ed. New York: OUP, 1997.
Cita MLA (9th ed.)Sommer, Robert. A Practical Guide to Behavioral Research: Tools and Techniques. 4th ed. OUP, 1997.
Atenció: Aquestes cites poden no estar 100% correctes.