1. G. Alberti, L. Ambrosio, A geometrical approach to monotone functions inRn, 1996
2. Analytical foundations of the theory of quasi-conformal mapping inRn;Bojarski;Ann. Acad. Sci. Fenn. Ser. A I Math.,1983
3. On the differentiability of absolutely continuous functions;Calderón;Riv. Mat. Univ. Parma,1951
4. Sulle funzioni assolutamente continue in due variabili;Cesari;Ann. Scuola Norm. Sup. Pisa,1941
5. Sulle transformazioni continue;Cesari;Ann. Mat. Pura Appl.,1942