1. O. Axelsson, “On preconditioning and convergence acceleration in sparse matrix problems”, CERN Data Handling Division Report, 74–10, 1974.
2. “A derivation of conjugate gradients”;Beale,1972
3. “A quasi-Newton method can be obtained from a method of conjugate directions”;Best;Mathematical Programming,1978
4. “A combined conjugate gradient quasi-Newton minimization algorithm”;Buckley;Mathematical Programming,1978
5. “Extending the relationship between the conjugate gradient and BFGS algorithms”;Buckley;Mathematical Programming,1978