For more information on all aspects of postcards, including postcard history, publishers, techniques, and dates, visit:
- Petrulis, Alan. Metropostcard.com. 2006–2018. http://www.metropostcard.com/index.html.
For more information on postcard history, visit:
- Smithsonian Institution Archives. "Postcard History." Greetings from the Smithsonian A Postcard History. https://siarchives.si.edu/history/featured-topics/postcard/postcard-history.
- United States Postal Service. "Stamps and Postcards." About. 2020. https://about.usps.com/who-we-are/postal-history/stamps-postcards.htm.
- WorldPostcardDay.com. "History of Postcards." History. https://worldpostcardday.com/history.
For more information on dating postcards, visit:
- Ellison, Todd. "Tips for determining when a U.S. postcard was published." Center of Southwest Studies, Fort Lewis College. 7 August 2006. https://www.fortlewis.edu/finding_aids/images/M194/PostcardDating.htm.
- Smithsonian Institution Archives. "Dating Postcards." Greetings from the Smithsonian A Postcard History. https://siarchives.si.edu/history/featured-topics/postcard/postcard-history.
For more information on Delaware postcards and the Delaware Postcard Collection, visit:
- Finding aid for the Delaware postcard collection
- Additional contextual information about the Delaware Postcard Collection is available by visiting this archived website from 2007: University of Delaware Library Digital Collections. "University of Delaware Library Post Card Collection." 10 June 2007. https://web.archive.org/web/20070610092735/http://fletcher.lib.udel.edu/collections/dpc/index.htm.
- Rude, Glenn A. and John P. Reid. "Delaware Postcards." Collecting Delaware Books. 1991–2021. http://jnjreid.com/cdb/postcards.html.
The entire Delaware Postcard Collection is viewable in greater detail on Artstor.