V. A. Rukavishnikov, E. V. Kuznetsova, “A scheme of a finite element method for boundary value problems with non-coordinated degeneration of input data”, Num. Anal. Appl., 2:3 (2009), 250–259
Rukavishnikov V.A., “Methods of Numerical Analysis for Boundary Value Problems with Strong Singularity”, Russ. J. Numer. Anal. Math. Model, 24:6 (2009), 565–590
Rukavishnikov V.A., Kuznetsova E.V., “Coercive estimate for a boundary value problem with noncoordinated degeneration of the data”, Differ. Equ., 43:4 (2007), 550–560
Arroyo D., Bespalov A., Heuer N., “On the Finite Element Method for Elliptic Problems with Degenerate and Singular Coefficients”, Math. Comput., 76:258 (2007), 509–537
E. V. Kashuba, V. A. Rukavishnikov, “On the $p$-version of the finite element method for the boundary value problem with singularity”, Sib. zhurn. vychisl. matem., 8:1 (2005), 31–42
Bespalov A., “Orthogonal Systems of Singular Functions and Numerical Treatment of Problems with Degeneration of Data”, Adv. Comput. Math., 19:1-3 (2003), 159–182