The pricing and yield formulas for fixed-income securities come from:
 Golub, B.W. and L.M. Tilman. Risk Management: Approaches for Fixed Income Markets. Wiley, 2000.
 Martellini, L., P. Priaulet, and S. Priaulet. Fixed Income Securities. Wiley, 2003.
 Mayle, Jan. Standard Securities Calculation Methods. New York: Securities Industry Association, Inc. Vol. 1, 3rd ed., 1993, ISBN 1-882936-01-9. Vol. 2, 1994, ISBN 1-882936-02-7.
 Tuckman, B. Fixed Income Securities: Tools for Today's Markets. Wiley, 2002.
In many cases these formulas compute the price of a security given yield, dates, rates, and other data. These formulas are nonlinear, however; so when solving for an independent variable within a formula, Financial Toolbox™ software uses Newton's method. See any elementary numerical methods textbook for the mathematics underlying Newton's method.