Gaya APA

LEEDY, P, D., ORMROD, J, E. (2019). PRACTICAL RESEARCH : PLANNING AND DESIGN TWELFTH EDITION (ED. 12). UNITED KINGOM: PEARSON EDUCATION LIMITED.

Gaya MLA

LEEDY, PAUL, D.., ORMROD, JEANNE, ELLIS. "PRACTICAL RESEARCH : PLANNING AND DESIGN TWELFTH EDITION". ED. 12 UNITED KINGOM: PEARSON EDUCATION LIMITED, 2019. Text.