Gaya APA

Heller, R. (Prancis : Unesco, 19). New trends in biology teaching. Vol. 2 . Prancis : Unesco, 1969: Prancis : Unesco, 1969.

Gaya MLA

Heller, R. "New trends in biology teaching. Vol. 2". Prancis : Unesco, 1969: Prancis : Unesco, 1969, Prancis : Unesco, 19. Text.