@Article{ Mag14, author = { Magnani, Valentino }, title = { On a measure-theoretic area formula }, journal = { Proc. Roy. Soc. Edinburgh Sect. A }, year = { 2015 }, volume = { 145 }, pages = { 885-891 }, URL = { http://cvgmt.sns.it/paper/2331/ }, note = { cvgmt preprint} }