Gaya APA
dkk., R, S, A. (1977).
The Encyclopedia Americana International Edition: Orley to Photographic Telescope (Vol.21).
New York:
Americana Corporation.
Gaya MLA
dkk., Robert, S., Anderson,.
"The Encyclopedia Americana International Edition: Orley to Photographic Telescope".
Vol.21
New York:
Americana Corporation,
1977.
Text.