1. Photochromic Silicate Glasses Sensitized by Silver Halides
2. (b)W. H. Armistead, and S. D. Stookey , "Phototropic Material and Article Made Therefrom," U.S. Pat. 3,208,860, Sept. 28, 1965 .
3. (c)R. A. Eppler, and S. D. Stookey , "Glass Composition and Method of Producing Phototropic Body," U.S. Pat. 3,197,297, 1965 .
4. 2G. P. Smith ; Paper No. 108, 9 pp. (in English) in Proceedings of VIIth International Glass Congress, Brussels, 1965, Vol. 1 . Institut National du Verre, Charleroi, and Federation de L'Industrie du Verre, Brussels, 1966 .
5. Chameleon in the sun: photochromic glass