21. Letter from Tracy M. Sonneborn to Max Delbruck Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 2 March 1949 Genre: Letters (correspondence)
22. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 4 January 1951 Genre: Letters (correspondence)
23. Letter from Tracy M. Sonneborn to Esther Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: June 1952 Genre: Letters (correspondence)
24. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 14 October 1952 Genre: Letters (correspondence)
25. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 29 April 1968 Genre: Letters (correspondence)
26. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 26 October 1967 Genre: Letters (correspondence)
27. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 31 January 1977 Genre: Letters (correspondence)
28. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 23 August 1976 Genre: Letters (correspondence)
29. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 10 October 1967 Genre: Letters (correspondence)
30. Letter from Tracy M. Sonneborn to Joshua Lederberg Creator: Sonneborn, T. M. (Tracy Morton), 1905-1981 Date: 1 July 1976 Genre: Letters (correspondence)