Gurley Cox's Stadia Computer Circular Slide Rule

Chicago citation style
W. & L. E. Gurley. Gurley Cox's Stadia Computer Circular Slide Rule. ca 1921. Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Anmah_1214526&repo=DPLA. (Accessed November 12, 2018.)
APA citation style
W. & L. E. Gurley, (ca 1921) Gurley Cox's Stadia Computer Circular Slide Rule. Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Anmah_1214526&repo=DPLA
MLA citation style
W. & L. E. Gurley. Retrieved from the Digital Public Library of America <http://collections.si.edu/search/results.htm?q=record_ID%3Anmah_1214526&repo=DPLA>.
Note: These citations are programmatically generated and may be incomplete.