1. Adams R.: Sobolev Spaces. Academic Press, London (1975)
2. Bacuta C., Bramble J.H., Xu J.: Regularity estimates for elliptic boundary value problems in Besov spaces. Math. Comp. 72, 1577–1595 (2003)
3. Braess D.: Finite Elemente: Theorie, schnelle Löser und Anwendungen in der Elastizitätstheorie. Springer-Verlag, New York (1997)
4. Dautray, R., Lions, J.L.: Evolution Problems I. In: Mathematical Analysis and Numerical Methods for Science and Technology, vol. 5. Springer-Verlag, New York (1995)
5. Dautray, R., Lions, J.L.: Functional and Variational Methods. In: Mathematical Analysis and Numerical Methods for Science and Technology, vol. 2. Springer-Verlag, New York (1995)