1. The Finite Element Method for Elliptic Problems;Ciarlet,1978
2. Finite Difference Schemes for Differential Equations with Generalized Solutions;Samarskii,1987
3. Boundary problems for elliptic equations in domains with conical or angular points;Kondrat’ev;Trans. Mosc. Math. Soc.,1967
4. Boundary-value problems for partial differential equations in non-smooth domains
5. On weak solutions of the Dirichlet and Neumann problems;Maz’ya;Trans. Mosc. Math. Soc.,1971