1. Ullmanns Encyclopedia of Industrial Chemistry, fifth ed., vol. A6, 1996, p. 330.
2. L.A. Mattano, US Patent 2,727,075 (1955), to Standard Oil Company.
3. J.W. Angelkorte, US Patent 2,920,09 (1960), to Union Carbide Corporation.
4. G.A. Olah, W.S. Tolgyesi, R.E.A. Dear, J. Org. Chem. 27 (1962) 3441, 3449.