1. J.W. Daniel, W.B. Gragg, L. Kaufman and G.W. Stewart, “Reorthogonalization and stable algorithms for updating the Gram-Schmidt QR factorization”,Mathematics of Computation 30 (1976) 772–795.
2. G.H. Golub and M.A. Saunders, “Linear least squares and quadratic programming”, in: J. Abadie, ed.,Integer and nonlinear programming (North-Holland, Amsterdam, 1970) pp. 229–256.
3. C.L. Lawson and R.J. Hanson,Solving least squares problems (Prentice Hall, Englewood Cliffs, NJ, 1974).
4. C. Lemarechal, “Combining Kelley's and conjugate gradient methods”, Abstracts, 9th International symposium on mathematical programming, Budapest (1976).
5. K. Schittkowski and J. Stoer, “A factorization method for constrained least squares problems with data changes, part 1: theory”, Institut für Angewandte Mathematik und Statistik der Universität Würzburg, Preprint No. 20 (1976).