Higuchi and Guttman, "NMR Evidence for Self-Association of Theophylline in Aqueous Solution: A Response,", 1971, Box: 11, Folder: 22. Personal papers of Takeru Higuchi, PP 359. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/124656 Accessed May 18, 2024.