1. Minchak, R.J. US Patent 4, 426, 502, issued 17/01/1984.
2. Matejka, L, Houtman, C and Macosko, C.W. (1985) J. Appl. Polym. sci. 30, 2787–2803.
3. Grubbs, R. H; Johnson, L. K.; Nguyen; S. T. US Patent No. 5, 312, 940, issued 5/17/1994.
4. Grubbs, R. H; Johnson, L. K.; Nguyen; S. T. US Patent No. 5, 342, 909, issued 8/30/1994.
5. Grubbs, R.H.; Nguyen, S.T.; Johnson, L.K. US Patent No. 5, 710, 298, issued 1/20/1998.