Avecillas Jara, Alberto SantiagoDefas Toledo, Vilma LorenaMora Oleas, Janeth Catalina2014-06-272014-06-271993http://dspace.ucuenca.edu.ec/handle/123456789/15666application/pdfspaopenAccesshttp://creativecommons.org/licenses/by-nc-sa/3.0/ec/FisicabachelorThesis