D. Šimonová and P. Tichý,
When does the Lanczos algorithm compute exactly?,
Electronic Transactions on Numerical Analysis, Vol. 55, pp. 547-567, 2022.
G. Meurant, J. Papež, and P. Tichý,
Accurate error estimation in CG,
Numerical Algorithms, Vol. 88, pp. 1337-1359, 2021.
How to control the accuracy of error estimates in CG?
Householder Symposium XXI, Italy (June 12-17, 2022).