Direct illumination from across passage not very effective because of dirty formation. The Bee Hive, Oregon Caves.

Chicago citation style
Department of the Interior. National Park Service. Oregon Caves National Monument. 1934-11/1971. Direct illumination from across passage not very effective because of dirty formation. The Bee Hive, Oregon Caves.. 1935. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/298934. (Accessed September 19, 2018.)
APA citation style
Department of the Interior. National Park Service. Oregon Caves National Monument. 1934-11/1971, (1935) Direct illumination from across passage not very effective because of dirty formation. The Bee Hive, Oregon Caves.. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/298934
MLA citation style
Department of the Interior. National Park Service. Oregon Caves National Monument. 1934-11/1971. Retrieved from the Digital Public Library of America <http://catalog.archives.gov/id/298934>.
Note: These citations are programmatically generated and may be incomplete.