https://www.kshs.org/kansapedia/pogo-comic-strip/15641
http://okeswamp.com/your-visit/pogo-and-walt-kelly/
http://ead.ohiolink.edu/xtf-ead/view?docId=ead/OhCoUCR0013.xml
http://whirledofkelly.blogspot.com/
https://www.cbr.com/walt-kellys-pogo-comics-reprinted-by-hermes-press/