References

[1]
C. Johnson. Numerical Solution of Partial Differential Equations by the Finite Element Method (Dover Publications, 2009).
[2]
J. Whiteley. Finite Element Methods, A Practical Guide (Springer, 2017).
[3]
S. C. Brenner and R. Scott. The mathematical theory of finite element methods. 3 Edition, Texts in applied mathematics (Springer, New York, NY, 2007).
[4]
D. N. Arnold, F. Brezzi, B. Cockburn and L. D. Marini. Unified analysis of discontinuous Galerkin methods for elliptic problems. SIAM J. Numer. Anal. 39, 1749–1779 (2002).