https://writingcenter.gwu.edu/online-citation-resources George Washington University
https://owl.english.purdue.edu/owl/section/2/ Purdue OWL
https://writing.wisc.edu/Handbook/Documentation.html University of Wisconsin Madison
https://writing.colostate.edu/guides/index.cfm?categoryid=11&title=2 Colorado State University
https://www.mla.org/MLA-Style MLA
http://www.chicagomanualofstyle.org/home.html Chicago Manual of Style