@book {eSayrol02, title = {Senyals i sistemes anal{\`o}gics: una introducci{\'o} pr{\`a}ctica}, year = {2002}, isbn = {84-8301-610-9}, url = {http://www.edicionsupc.es}, author = {Elisa Sayrol and Gasull, A. and Moreno, A. and Salavedra, J. and Vallverdu, F.} }