Numerically stable algorithm for pole assignment of linear single-input systems Petko Hr. Petkov; Nicolai D. Christov; Michail M. Konstantinov — 1986 Kybernetika
Invariants and canonical forms for linear multivariable systems under the action of orthogonal transformation groups Michail M. Konstantinov; Petko Hr. Petkov; Nicolai D. Christov — 1981 Kybernetika
Perturbation analysis of the discrete Riccati equation Michail M. Konstantinov; Petko Hr. Petkov; Nicolai D. Christov — 1993 Kybernetika