Higuchi et. al, "Studies on Pharmaceutical Powders and the State of Subdivision. II. Surface Area Measurements of Some Pharmaceutical Powders by the Low-Temperature Nitrogen Adsorption Isotherm Technique,", 1949, Box: 11, Folder: 116. Personal papers of Takeru Higuchi, PP 359. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/124750 Accessed June 16, 2024.