1. 1C. M. Riley , Possibilities of Bloating Clays in Minnesota, Minnesota Geological Survey, Summary Report No. 5, 1950 .
2. 2T. E. Jackson , p.43 , discussion of the paper "Changes in Color of Clays on Ignition in Clayware Kilns," by Arthur Hopwood, Trans. Ceram. Soc. (Engl.), 1903 , pp.43 -43 .
3. 4Wilson Hewitt , Ceramics-Clay Tcchnology . McGraw-Hill Book Co., Inc., New York, 1927 . 296 pp.; Ceram.Abstracts, 6 [11 ] 296 (1927 ).