Babbie, E. R. (1986). The practice of social research. Wadsworth.
Cita Chicago (17th ed.)Babbie, Earl R. The Practice of Social Research. Belmont, Calif.: Wadsworth, 1986.
Cita MLA (9th ed.)Babbie, Earl R. The Practice of Social Research. Wadsworth, 1986.
Atenció: Aquestes cites poden no estar 100% correctes.