Further Reading on Postcards
Gable, Walter. "A History of Picture Postcards." The Written History of Seneca County, New York. Seneca County, New York, http://www.co.seneca.ny.us/wp-content/uploads/2020/01/Postcards-History-ADA.pdf
Historian. "Stamped Cards and Postcards." United States Postal Service, Sept. 2014, https://about.usps.com/who-we-are/postal-history/stamped-cards-and-postcards.pdf
"Postcard History." Smithsonian Institution Archives, https://siarchives.si.edu/history/featured-topics/postcard/postcard-history