1. Bielski WR, Galka A, Telega JJ. The complementary energy principle and duality for geometrically nonlinear elastic shells. I. Simple case of moderate rotations around a tangent to the middle surface. Bulletin Polish Academy Sci Tech Sci. 1988;38:7–9.
2. Bielski WR, Telega JJ. A contribution to contact problems for a class of solids and structures. Arch Mech. 1985;37(4–5):303–20, Warszawa.
3. Telega JJ. On the complementary energy principle in non-linear elasticity. Part I: Von Karman plates and three dimensional solids. C.R. Acad Sci Paris Serie II. 1989;308:1193–8; Part II: Linear elastic solid and non-convex boundary condition. Minimax approach, ibid: 1313–1317.
4. Galka A, Telega JJ. Duality and the complementary energy principle for a class of geometrically non-linear structures. Part I. Five parameter shell model; Part II. Anomalous dual variational priciples for compressed elastic beams. Arch Mech. 1995;47:677–98, 699–724.
5. Toland JF. A duality principle for non-convex optimisation and the calculus of variations. Arch Rat Mech Anal. 1979;71(1):41–61.