This primary source comes from the Collection DDE-1243: Oveta Culp Hobby Papers.
Full Citation: Polio Age-Specific Acute Admission Rates, 1954; 5/1955; Salk Vaccine - April and May 1955; Personal Files, 1929 - 1960; Collection DDE-1243: Oveta Culp Hobby Papers. [Online Version, https://docsteach.org/documents/document/1-polio-age-specific-acute-admission-rates-1954, March 28, 2023]