H=W It's a paper showing that two methods of defining Sobolev spaces, one which uses H's with subscripts and superscripts and one that uses W's, give rise to the same spaces. Unfortunately I don't remember the citation information. **Citation information** @ARTICLE{MeySer1964, author = {Meyers, Norman G. and Serrin, James}, title = {{H = W}}, journal = {Proc. Natl. Acad. Sci. USA}, year = {1964}, volume = {51}, pages = {1055-1056}, number = {6}, file = {MeySer1964.pdf:MeySer1964.pdf:PDF}, owner = {ww278}, timestamp = {2010.05.03}, url = {http://www.pnas.org/content/51/6/1055.short} }