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Higuchi et. al, "Improved Delivery through Biological Membranes.   4. Prodrugs of L-Dopa,", 1977, Box: 10, Folder: 160. Personal papers of Takeru Higuchi, PP 359. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/124584 Accessed December 25, 2025.