1. J. P. Briggs, R. R. Hudgins andP. L. Silveston, J. Chromatogr. Sci.14, 335 (1976).
2. P. Centola, G. Terzaghi, R. Del Rosso, Chimica el' Industria (Milano)54, 219 (1972).
3. M. Aubry, B. Gilot, J. Chromatogr.32, 180 (1968).
4. R. L. Bond, W. J. Mullin andF. J. Pinchin, Chem. and Ind. 1902 (1963).
5. R. A. Mancini, PhD Thesis, Northwestern University, Evanston, Illinois, USA (1972).