1. Proc. Roy;Fox J .;Soc. A,1962
2. Chapm an S. & Cowling T. G. i960 The mathematical theory of non-uniform gases 2nd ed. Cam bridge U niversity Press.
3. D algarno A. & L ynn N. 1956 Proc.
4. D algarno A. i960 Proc. Phys. Soc. 75 374.
5. Astrophys;Edm F .;J .,1957