Study of linear information for classes of polynomial equations. K. Sikorski — 1989 Aequationes mathematicae
Optimal Solution of Nonlinear Equations Satisfying a Lipschitz Condition. K. Sikorski — 1984 Numerische Mathematik
Asymptotic Near Optimality of the Bisection Method. K. Sikorski; G.M. Trojan — 1990 Numerische Mathematik