1. M. M. Frocht, “Photoelasticity”, John Wiley and Sons, Vol. 1 (1941), Vol, 2 (1948)
2. J. A. O’Keefe, “Tektites and Their Origin”, Elsevier (1976)
3. R. H., Brill, Corning Museum of Glass, Corning, N. Y., Private Communication (1981)
4. “The Glassmakers of Herat”, A Documentary Film Filmed and Produced by Elliot Erwitt for The Corning Museum of Glass, 1977, available from Corning Museum of Glass.
5. J. Charleston, pp. 9-33, Vol. 20. J. of Glass Studies, (1978)