@Misc{ ambmartar98, author = { Ambrosio, Luigi and Fonseca, Irene and Marcellini, Paolo and Tartar, Luc }, title = { On a Volume Constrained Variational Problem }, journal = { To appear on Arch. Rat. Mech. Anal. }, year = { 1998 }, pages = { }, URL = { http://cvgmt.sns.it/paper/1362/ }, note = { cvgmt preprint} }