HRF subgroup consists of general correspondence (1947-1985), interoffice correspondence (1947-1983), financial records (1947-1985), laboratory records (1948-1982), legal documents (1948-1981), minutes and organizational materials (1947-1984), photos (1948-1971), printed material (1948-1984), reports (1950-1983), subject files (1949-1982), miscellany, and clippings (1946-1983), chiefly relating to the scientific work of the foundation, particularly the development of Holter electrocardiography equipment, portable devices used in monitoring heart beats (produced by Del Mar Avionics Corporation, of California). Persons represented include Wilford R. Glasscock, HRF associate physicist (1949-1968), J.A. Gengerelli, of California, research associate (1947-1985), and Lawrence E. Hinkle, of New York, N.Y. Norman J. Holter subgroup includes bibliographical information, general correspondence (1914-1983), interoffice correspondence (1961-1973), diaries (1924-1945), financial records (1935-1975), school notes and records (1927-1979), speeches and writings (1940-1983), and subject files (1937-1984), documenting Holter's personal life, investments, scientific and professional associations, civil defense work, interest in radioisotopes in medicine, and other activities.

Norman J. Holter/U.S. Navy subgroup (1941-1947) contains general correspondence, interoffice correspondence, diaries, press releases, subject files, and clippings, chiefly concerning Holter's work on bombs and wave reaction during and after World War II, and including materials from Operation Crossroads, the first post-war atomic bomb test expedition, conducted at Bikini Atoll in the Pacific. Horman J. Holter/University of California San Diego subgroup (1964-1966) consists of general correspondence, interoffice correspondence, subject files, and miscellany, chiefly relating to Holter's duties as assistant chancellor of the university. Society of Nuclear Medicine subgroup (1954-1983) includes general correspondence, financial records, minutes, organization materials, speeches, programs of annual meetings, and miscellany, including documentation on Holter's activities as founding member and service as treasurer and president (1957). Includes photos, artifacts (including some original monitoring equipment), and sound recordings (speeches, etc.).