1. 1Horst Scholze, Hans-Otto Mulfinger, and Helmut Franz ; pp.230 -48 (in German) inAdvances in Glass Technology . Plenum Press, New York, 1962 .
2. 2R. K. Day ; pp.235 -49 inSymposium on Glass Refining, Paris, June 1955; Union Scientifique Continentale du Verre, Charleroi, Belgium, 1957 .