Higuchi et. al, "Facilitated Reversible Formation of Amides from Carboxylic Acid In Aqueous Solutions. III. Reaction of Citric Acid with Aromatic Amines,", 1964, Box: 10, Folder: 138. Personal papers of Takeru Higuchi, PP 359. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/124562 Accessed May 25, 2024.