1. A.E.H. Love, A treatise on the mathematical theory of elasticity, 4th Ed. Cambridge UP (1926).
2. G. Fichera, Problemi elastostatici con vincoli unilaterali: il problema di Signorini con ambigue condizioni al contorno, Mem. Ac. N. Lincei 8, 7 (1964) 116–140.
3. G. Duvaut, J.-L. Lions, Les inéquations en mécanique et en physique, Dunod, Paris, 1972.
4. P.D. Panagiotopoulos, A non linear programming approach to the unilateral contact and friction-boundary value problem in the theory of elasticity, Ing. Arch. 44 (1975) 421–432.
5. K.L. Johnson, Tangential tractions and microslip in rolling contact, In: Proc. Symp. Rolling Contact Phenomena, Elsevier (1962) 6–28.