1. U. S. Pat. 2,130,523 (9/20/38), assigned to Du Pont Co.
2. and U. S. Pat. 2,594,144 (4/22/52), assigned to Wing-foot Corp.
3. Synthetic Fiber Developments in Germany, Textile Research Institute, New York, 1946;
4. and German Pat. 818,580 (1951). assigned to Farbenfabriken A.-G.;
5. and German Pat. 904,471 (2/18/54), assigned to Farbwerke Hoechst A.-G.;