1. Letter from Lewis Hackett to Fred L. Soper Publication: Produced: 12 October 1955 Subject(s): Financial SupportMosquito ControlYellow Fever Vaccine Archival Collection: The Fred L. Soper Papers (Profiles in Science)
2. Letter from Fred L. Soper to Lewis Hackett Publication: Produced: 18 October 1955 Subject(s): Financial SupportMosquito ControlYellow Fever Vaccine Archival Collection: The Fred L. Soper Papers (Profiles in Science)
3. Letter from Lewis Hackett to Fred L. Soper Publication: Produced: 12 January 1959 Subject(s): Insect ControlDDTYellow Fever Vaccine Archival Collection: The Fred L. Soper Papers (Profiles in Science)
4. Letter from Fred L. Soper to Lewis Hackett Publication: Produced: 20 January 1959 Subject(s): DDTInsect ControlYellow Fever Vaccine Archival Collection: The Fred L. Soper Papers (Profiles in Science)
