O pioneers!

Chicago citation style
Cather, Willa, 1873-1947. O pioneers!. [1929]. Retrieved from the Digital Public Library of America, http://catalog.hathitrust.org/Record/000624034. (Accessed December 19, 2018.)
APA citation style
Cather, Willa, 1873-1947, ([1929]) O pioneers!. Retrieved from the Digital Public Library of America, http://catalog.hathitrust.org/Record/000624034
MLA citation style
Cather, Willa, 1873-1947. Retrieved from the Digital Public Library of America <http://catalog.hathitrust.org/Record/000624034>.
Note: These citations are programmatically generated and may be incomplete.