"Excavation operations on the east side. The upper shovel is working at elevation 975 and the lower shovel at elevation 925. Excavating rock in the east abutment and power house area. Forms for the foundation of the Eastmix concrete plant appear on the left."

Chicago citation style
Department of the Interior. Bureau of Reclamation. Engineering and Research Center. 5/18/1981-3/4/1988. "Excavation operations on the east side. The upper shovel is working at elevation 975 and the lower shovel at elevation 925. Excavating rock in the east abutment and power house area. Forms for the foundation of the Eastmix concrete plant appear on the left.". 1936-02-27. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/294262. (Accessed October 15, 2018.)
APA citation style
Department of the Interior. Bureau of Reclamation. Engineering and Research Center. 5/18/1981-3/4/1988, (1936-02-27) "Excavation operations on the east side. The upper shovel is working at elevation 975 and the lower shovel at elevation 925. Excavating rock in the east abutment and power house area. Forms for the foundation of the Eastmix concrete plant appear on the left.". Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/294262
MLA citation style
Department of the Interior. Bureau of Reclamation. Engineering and Research Center. 5/18/1981-3/4/1988. Retrieved from the Digital Public Library of America <http://catalog.archives.gov/id/294262>.
Note: These citations are programmatically generated and may be incomplete.