Gastelum Soto, Anabel. ¬ęProficiency Level in English Teachers of the Seventh-Day Adventist Secondary Schools in the Northern Mexican Union Conference¬Ľ. anuario2020 1, no. 1 (agosto 3, 2020): 1-4. Accedido febrero 27, 2024. http://anuarioinvestigacion.um.edu.mx/index.php/a2020/article/view/42.