1. Ashby, Steven F., Thomas A. Manteuffel, and Paul E. Saylor. “A Taxonomy for Conjugate Gradient Methods,” Lawrence Livermore National Laboratory Report UCRL-98508, March 1988, submitted to SIAM Journal on Numerical Analysis.
2. “A Generalized Conjugate Gradient Method for Nonsymmetric Systems of Linear Equations,”;Concus,1976
3. “Variational iterative methods for nonsymmetric systems of linear equations,”;Eisenstat;SIAM Journal on Numerical Analysis,1983
4. “Necessary and sufficient conditions for the existence of a conjugate gradient method,”;Faber;SIAM Journal on Numerical Analysis,1984
5. “Orthogonal error methods,”;Faber;SIAM Journal on Numerical Analysis,1987