1. 1) P. Grisvard, Elliptic Problems in Nonsmooth Domains, Pitman, Boston, 1985.
2. 2) A. Mizutani, On the finite element method for the biharmonic Dirichlet problem in polygonal domains; quasi-optimal rate of convergence, Jpn. J. Ind. Appl. Math., 22 (2005), 45-56.
3. 3) C. Wieners, Numerical enclosures for solutions of the Navier-Stokes equations for small Reynolds numbers, in: in: Numerical methods and error bounds, Proc. of the IMACS-GAMM international symposium, Oldenburg, Germany, July 9-12, 1995, G. Alefeld, et al., eds., Math. Res., Vol. 89, pp. 280-286, Akademie Verlag, Berlin, 1996.
4. 4) U. Storck, Numerical enclosure for solutions of the incompressible stationary Navier-Stokes equation in two dimensions, Book of Abstracts of SCAN 2000/Interval 2000 held in Karlsruhe, Germany, September 19-22, 2000, pp.118.
5. 5) M. T. Nakao, K. Nagatou and K. Hashimoto, Numerical enclosure of solutions for two dimensional driven cavity problems, in: Proc. of European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2004) P. Neittaanmäki, et al., eds., 2004.