1. Adams, R. A.: Sobolev Spaces, Academic Press, New York, 1975
2. Bojarski, B.: Remarks on Sobolev Imbedding Inequalities. In: Lecture Notes in Math., Vol. 1351, Springer-Verlag, Berlin, 1989, 52–68
3. Report No. 29;J Boman,1982
4. Buckley, S. M., Koskela, P.: Sobolev-Poincaré implies John. Res. Lett. 2, 577–594 (1995)
5. Buckley, S. M., Koskela, P., Lu, G. Z.: Boman equals John, In: XVIth Rolf Nevanlinna Colloquium (Joensuu, 1995), 91–99, de Gruyter, Berlin, 1996