Oscar A. Hallberg speaking at an unidentified gathering

Chicago citation style
Oscar A. Hallberg speaking at an unidentified gathering. 1900. Retrieved from the Digital Public Library of America, http://heritage.sonomalibrary.org/cdm/ref/collection/p15763coll11/id/4755. (Accessed December 11, 2018.)
APA citation style
(1900) Oscar A. Hallberg speaking at an unidentified gathering. Retrieved from the Digital Public Library of America, http://heritage.sonomalibrary.org/cdm/ref/collection/p15763coll11/id/4755
MLA citation style
Retrieved from the Digital Public Library of America <http://heritage.sonomalibrary.org/cdm/ref/collection/p15763coll11/id/4755>.
Note: These citations are programmatically generated and may be incomplete.