Paggi, Marco and Carpinteri, Alberto and Zavarise, Giorgio  A unified interface constitutive law for the study of fracture and contact problems in heterogeneous materials.   In:  Analysis and Simulation of Contact Problems.   Lecture Notes in Applied and Computational Mechanics  (27).  Springer-Verlag, pp. 297-304.  ISBN 978-3-540-31761-6      (2006)