1. Abramowitz, M.: 1964, in M. Abramowitz and I. A. Stegun (eds.),Handbook of Mathematical Functions, Dover, New York.
2. Eddington, A. S.: 1926, inThe Internal Constitution of the Stars, Cambridge University Press, Cambridge.
3. Kramer, E. E.: 1981, inThe Nature and Growth of Modern Mathematics, Princeton University Press, New Jersey.