1. Recommendation for Leon Heppel for the Guggenheim Foundation Fellowship Creator: Singer, Maxine Date: [December 1974] Genre: ProposalsLetters (correspondence)
2. Letter from Maxine Singer to Paul Shullenberger Creator: Singer, Maxine Date: 12 November 1982 Genre: Letters (correspondence)
3. Letter from Maxine Singer to Leon A. Heppel Creator: Singer, Maxine Date: 21 October 1955 Genre: Letters (correspondence)
4. Letter from Leon A. Heppel to Maxine Singer Creator: Heppel, Leon A.National Institutes of Health (U.S.) Date: 27 October 1955 Genre: Letters (correspondence)