[Letter] 1849 January 17 [to] Robert Allan / Alan Stevenson.

Chicago citation style
Stevenson, Alan, 1807-1865. [Letter] 1849 January 17 [to] Robert Allan / Alan Stevenson.. 1849-01-17. Retrieved from the Digital Public Library of America, http://cdm.lib.lehigh.edu/cdm/ref/collection/letters/id/334. (Accessed December 15, 2018.)
APA citation style
Stevenson, Alan, 1807-1865, (1849-01-17) [Letter] 1849 January 17 [to] Robert Allan / Alan Stevenson.. Retrieved from the Digital Public Library of America, http://cdm.lib.lehigh.edu/cdm/ref/collection/letters/id/334
MLA citation style
Stevenson, Alan, 1807-1865. Retrieved from the Digital Public Library of America <http://cdm.lib.lehigh.edu/cdm/ref/collection/letters/id/334>.
Note: These citations are programmatically generated and may be incomplete.