1. P.H. Desai, D.A. Keyworth, M.Y. Asim, T.A. Reid, A.H. Pichel, NPRA Paper AM-92-44, 1992.
2. E.G. Wollaston, W.L. Forsythe, I.A. Vasalos, Oil Gas J. August 2 (1971) 64.
3. R.F. Wormsbecher, G.D. Weatherbee, G. Kim, T.J. Dougan, NPRA Paper AM-93-55, 1993.
4. T. Myrstad, H. Engan, B. Seljestokken, E. Rytter, Appl. Catal., in press.