Παραπομπή APA

Willock, C. (1974). Africa's rift valley. Time-Life Books.

Παραπομπή Chicago Style

Willock, Colin. Africa's Rift Valley. Amsterdam: Time-Life Books, 1974.

Παραπομπή MLA

Willock, Colin. Africa's Rift Valley. Time-Life Books, 1974.