Mixed Finite Elements, Compatibility Conditions, and Applications Lectures given at the C.I.M.E. Summer School held in Cetraro, Italy June 26–July 1, 2006 - Boffi, Daniele; Brezzi, Franco; Demkowicz, Leszek F.; Durán, Ricardo G.; Falk, Richard S.; Fortin, Michel (Springer Berlin Heidelberg, 2008)