1390-65421390-6542S1390-6542201400030001510.29019/enfoqueute.v5n3.41Ecuador000920140009201453152420082322148-5820112944472 - 4772006201220084110102011182011272720101193320025522181-912013200820045221212005201020111201020142014200152662011311183-9220132013Sao Paulo, Brasil 200810112009111120132014Valencia, España 2014672220132013201116112006