1. 1C. W. Parmelee , Ceramic Glazes , p. 105 . Industrial Publications, Inc., Chicago, 1948 . 105 pp.Ceram. Abstr, 1948 , p. 105 .
2. 2(a) Hewitt Wilson , Ceramics-Clay Technology , pp. 180 -81 . McGraw-Hill Book Co., Inc., New York, 1927 . 180 pp.; Ceram. Abstr., 6 [11 ] 180 (1927 ).
3. (b)F. H. Norton , Refractories , 3d ed. , revised, p. 186 . McGraw-Hill Book Co., Inc., New York, 1949 . 186 pp.Ceram. Abstr., 1949 , p. 186 .
4. (c)Walter Drum , Iehrbuch der Dentalkeramik (Dental Ceramics Manual) , p. 82 . Berlinische verlagsantalt, Berlin, 1939 . 82 pp.