1. R. Fletcher,Practical methds of optimization, Volume 1: Unconstrained optimization (Wiley, Chichester, 1980).
2. M.J.D. Powell, “Convergence properties of a class of minimization algorithms”, in: O.L. Managasarian, R.R. Meyer and S.M. Robinson, eds.,Nonlinear Programming 2 (Academic Press, New York, 1975).
3. D.C. Sorensen, “An example concerning quasi-Newton estimation of a sparse Hessian”,SIGNUM Newsletter 16(2) (1981) 8–10.
4. D.C. Sorensen, “Trust region methods for unconstrained optimization” in: M.J.D. Powell ed.,Nonlinear Optimization 1981 (Academic Press, London, 1982).