1. Chem. Eng-London, 28 June (1990) 15.
2. F. Merger, H.J. Foerster, US Patent 4,408,079 (1982), to BASF AG.
3. G. Duembgen, G. Fouquet, R. Krabetz, E. Lucas, F. Merger, F. Nees, US Patent 4,496,770 (1983), to BASF AG.
4. G.P. Hagen, US Patent 4,433,174 (1984), to Standard Oil Co.
5. R.A. Montag, S.T. McKenna, European Patent 255,395 (1988), to Amoco Corp.