1. G. A. Baker Jr.,Essentials of Padé Approximants (Academic Press, New York, 1975), Chapter 8.
2. R. W. Haymaker and L. Schlessinger, inThe Padé Approximant in Theoretical Physics, G. A. Baker, Jr. and J. L. Gammel, eds. (Academic Press, New York, 1970), Chapter 11.
3. R. C. Dorf,Modern Control System (Addison-Wesley, London, 1970), p. 113.
4. D. J. Scalapino, inSuperconductivity, R. D. Parks, ed. (Marcel Dekker, New York, 1969), Chapter 10.
5. W. L. McMillan and J. M. Rowell, inSuperconductivity, R. D. Parks, ed. (Marcel Dekker, New York, 1969), Chapter 11.