I thought they were Mark McGwire historical markers

Chicago citation style
I thought they were Mark McGwire historical markers. 1998. Retrieved from the Digital Public Library of America, https://digital.lib.utk.edu/collections/islandora/object/cDanielCartoon%3A1004. (Accessed October 20, 2018.)
APA citation style
(1998) I thought they were Mark McGwire historical markers. Retrieved from the Digital Public Library of America, https://digital.lib.utk.edu/collections/islandora/object/cDanielCartoon%3A1004
MLA citation style
Retrieved from the Digital Public Library of America <https://digital.lib.utk.edu/collections/islandora/object/cDanielCartoon%3A1004>.
Note: These citations are programmatically generated and may be incomplete.