1. Abramowitz, M. and Stegun, I. E.: 1972, Handbook of Mathematical Functions, 10th printing, National Bureau of Standards, Washington, DC.
2. Bogdan, T. J. and Cally, P. S.: 1997, Proc. Roy. Soc. Lond. 453A, 943.
3. Christensen-Dalsgaard, J.: 1980, Monthly Notices R. Astr. Soc. 190, 765.
4. Deubner, F.-L. and Gough, D.: 1984, Ann. Rev. Astron. Astrophys. 22, 593.
5. Gough, D.: 1993, in J.-P. Zahn and J. Zinn-Justin (eds.), Astrophysical Fluid Dynamics, Elsevier, North Holland, pp. 449.