Letters written to him and copies of letters by him; manuscripts and reprints of his articles and papers; speeches; research data including notebooks; lecture notes, course descriptions, exams and other University-related material; papers (minutes of meetings, programs, etc.) relating to professional organizations, including American Association for the Advancement of Science, American Institute of Physics, American Physical Society and National Academy of Sciences. Covers his research on band spectra and physical constants as well as his academic career. Addition includes reprints, offprints, and miscellaneous publications.