1. R.A. Adams, Sobolev spaces, Vol.65ofPure and Applied Mathematics. Academic Press [A subsidiary of Harcourt Brace Jovanovich, Publishers], New York-London (1975).
2. Ahmad B., Alsaedi A., Brezzi F., Marini L.D. and Russo A., Equivalent projectors for virtual element methods.Comput. Math. Appl.66(2013) 376–391.
3. Arnold D.N. and Brezzi F., Mixed and nonconforming finite element methods: implementation, postprocessing and error estimates.RAIRO M2AN19(1985) 7–32.
4. Baran A.E. and Stoyan G., Gauss-Legendre elements: A stable, higher order non-conforming finite element family.Comput.79(2007) 1–21.
5. Beirão da Veiga L., Lipnikov K. and Manzini G., Arbitrary-order nodal mimetic discretizations of elliptic problems on polygonal meshes.SIAM J. Numer. Anal.49(2011) 1737–1760.