Gaya APA

Catalogin, L, O, C., WIDJAJA, H. (1975). The encyclopedia americana volume 21 orley to photographic telescope . New York: Encyclopedia Americana Corporation.

Gaya MLA

Catalogin, Library, Of, Conggress., WIDJAJA, H.A.W.. "The encyclopedia americana volume 21 orley to photographic telescope". New York: Encyclopedia Americana Corporation, 1975. Buku Teks.