F. W. Bowdish, A. Swineford, and N. Plummer, “Experimental Separation of Iron-Bearing Minerals from Certain Kansas Clays / Electron Microscopy of Fired Glaze Surfaces”, kgsbulletin, no. 102, pp. 122–142, Jan. 1953, doi: 10.17161/kgsbulletin.no.102.22073.