Gaya APA

Vol.20, G, E, O, K. (1993). Grolier encyylopedia of knowlwdge Vol.20 / Grolier Incorporated . : .

Gaya MLA

Vol.20, Grolier, Encyylopedia, Of, Knowlwdge. "Grolier encyylopedia of knowlwdge Vol.20 / Grolier Incorporated". : , 1993. Referensi.