On Conjugate Gradient Type Methods and Polynomial Preconditioners for a Class of Complex Non-Hermitian Matrices. Roland Freund — 1990 Numerische Mathematik
On a Class of Chebyshev Approximation Problems Which Arise in Connection with a Conjugate Gradient Type Method. Stephan Ruscheweyh; Roland Freund — 1986 Numerische Mathematik
QMR: a quasi-minimal residual method for non-Hermitian linear systems. Roland W. Freund; N.M. Nachtigall Numerische Mathematik
A look-ahead algorithm for the solution of general Hankel systems. Roland W. Freund; Hongyuan Zha — 1993 Numerische Mathematik