This primary source comes from the Collection DDE-WHCF: White House Central Files (Eisenhower Administration).
Full Citation: Telegram from Dr. Spencer to President Eisenhower Regarding the Distribution of Polio Vaccine; 4/15/1955; OF 117-I-1 Salk Polio Vaccine (6); Official Files, 1953 - 1961; Collection DDE-WHCF: White House Central Files (Eisenhower Administration); Dwight D. Eisenhower Library, Abilene, KS. [Online Version, https://www.docsteach.org/documents/document/telegram-dr-spencer-to-president-eisenhower-polio-vaccine, May 2, 2024]