1. Healy, J. V. and Yang, H. T.: 1972,Astron. Acta 17, 851.
2. Healy, J. V. and Yang, H. T.: 1973,Appl. Sci. Res. 21, 38.
3. Liu, J. T. C.: 1967,Astron. Acta 13, 369.
4. Marris, A. W. and Passman, S. L.: 1969,Arch. Rat. Mech. Anal. 32, 29.
5. Michael, D. H.: 1968,J. Fluid Mech. 31, 175.