1. R. M. Thomas and O. C. Slotterbeck, U.S. Pat. 2,243,658 (May 27, 1941).
2. R. M. Thomas and W. J. Sparks, U.S. Pat. 2,356,128 (Aug. 22, 1944).
3. W. J Sparks and R. M. Thomas, U.S. Pat. 2,356,129 (Aug. 22, 1944).
4. R. M. Thomas, I. E. Lightbown, W. J. Sparks, P. K. Frolich and E. V. Murphree, Ind. Eng. Chem.
32, 1283 (1940).
5. R. M. Thomas and W. J. Sparks, Synthetic Rubber, G. S. Whitby, ed. John Wiley & Sons, New York, 1963, ch. 24.