https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221743/
NIH
Morton Salt Company advertising blotter, circa 1925. From the collection of the University of Michigan Center for the History of Medicine.
Morton Salt Company advertising blotter, circa 1925. From the collection of the University of Michigan Center for the History of Medicine.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221743/