Cita APA (7th ed.)
Friend, D. V. (1987). Quantitative methods. Longman.
Cita Chicago (17th ed.)
Friend, D. V. Quantitative Methods. London ; New York: Longman, 1987.
Cita MLA (9th ed.)
Friend, D. V. Quantitative Methods. Longman, 1987.
Atenció: Aquestes cites poden no estar 100% correctes.