Israel Barrutia ; José Antonio Urquizo Maggia ; Samuel Isaias Acevedo https://retos.ups.edu.ec/index.php/granja/index.php/retos/article/view/17.2019.04/3238/index.php/retos/information/readers/index.php/retos/article/view/17.2019.06/index.php/retos/article/view/17.2019.04/index.php/retos/article/view/17.2019.10/3250/index.php/retos/issue/archive/index.php/retos/article/view/17.2019.05/index.php/retos/article/view/3122.
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