@Misc{ AmDeDeCr11, author = { Ambrosio, Luigi and Crasta, Graziano and De Cicco, Virginia and De Philippis, Guido }, title = { A nonautonomous chain rule in $W^{1,p}$ and in $BV$ }, journal = { Manuscripta Math. }, year = { 2012 }, pages = { }, URL = { http://cvgmt.sns.it/paper/1682/ }, note = { cvgmt preprint} }