REFERENCIAS

1. https://www.youtube.com/watch?v=HW_0VuFibOY 2. http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-74252013000100010 3. https://www.youtube.com/watch?v=qUZ8Pp--N7c&feature=share 4. https://www.youtube.com/watch?v=3B-TpnzFDNI 5. https://www.youtube.com/watch?v=34oeBS7dezY