United States. Children's Bureau and Eliot, Martha M., 1891-1978. The Effect of Tropical Sunlight on the Development of Bones of Children in Puerto Rico : A Roentgenographic and Clinical Study of Infants and Young Children with Special Reference to Rickets and Related Factors, Bureau Publication No. 217 , Washington, D.C: Government Printing Office, 1933, https://fraser.stlouisfed.org/title/8493, accessed on October 3, 2024.