[1] Adams R. A.: Sobolev spaces. Academic Press (1975), New York-San Francisco-London. MR 0450957 | Zbl 0314.46030

[2] Burenkov V. J.: Mollifying operators with variable step and their application to approximation by infinitely differentiable functions. Nonlinear analysis, Function Spaces and Applications, vol 2, Proceedings of the Spring School held in Písek, Teubner-Texte zur Mathematik, Band 49 (1982), Leipzig, 5-37. MR 0684996 | Zbl 0536.46021

[3] Gurka P.: Generalized Hardy's inequality for functions vanishing on both ends of the interval. (to appear in Analysis).

[4] Gurka P., Opic B.: Continuous and compact imbeddings in weighted Sobolev spaces I. Czechoslovak Math. J. 38 No. 4, (1988), 730-744. MR 0962916

[5] Gurka P., Opic B.: Continuous and compact imbeddings in weighted Sobolev spaces II. Czechoslovak Math. J. 39 No. 1, (1989), 78-94. MR 0983485

[6] Maz'ja V. G.: Sobolev spaces. Springer-Verlag, 1985. MR 0817985 | Zbl 0692.46023

[7] Opic B.: Hardy's inequality for absolutely continuous functions with zero limits on both ends of the interval. (to appear).

[8] Opic B., Gurka P.: $N$-dimensional Hardy inequality and imbedding theorems for weighted Sobolev spaces on unbounded domains. Function spaces, differential operators and nonlinear analysis; Proc. of the International Summer School on Function Spaces, Differential Operators and Nonlinear Analysis held in Sodankylä. Longman Scientic & Technical (1989), 108-124. MR 1041113 | Zbl 0695.46017