On the transfer of conditions as applied to solving two-dimensional boundary value problems
On the transformation theory of ordinary second-order linear symmetric differential equations
On two-sided difference methods for ordinary differential equations
On various properties of the solutions of third- and fourth-order linear differential equations
Optimization of the domain in elliptic unilateral boundary value problems by finite element method
Orthogonal bipolynomials
Oscillation in linear differential equations
Oscillation of Bôcher's pairs with respect to halflinear second order diff. equ.-s
Oscillation theory of higher-order ordinary and functional differential equations with forcing terms
Oscillation theory of self-adjoint equations and some its applications