1. William H. Beyer, ed.CRC Standard Mathematical Tables, 27th ed., CRC Press, Boca Raton, FL, 1984, pp. 182–192.
2. Carl B. Boyer,A History of Mathematics, Wiley, New York, 1968, p. 609.
3. David M. Burton,The History of Mathematics: Art Introduction, Wm. C. Brown, Dubuque, IA, 1988, p. 577.
4. An Application of Geography to Mathematics: History of the Integral of the Secant