Velis Cabezas, C. E., Arévalo Solórzano, J. A., Yanes Reyes, J. B., & Franco, R. (2009). Incidence of the previous english knowledge of fourth year students in the Bachelor of Arts in English Teaching reflected in their academic achievement through grades. San Salvador: Universidad de El Salvador.

Velis Cabezas, Carlos Edgardo, Jesús Adalberto Arévalo Solórzano, Jaime Benjamín Yanes Reyes, and Rhina Franco. Incidence of the Previous English Knowledge of Fourth Year Students in the Bachelor of Arts in English Teaching Reflected in Their Academic Achievement Through Grades. San Salvador: Universidad de El Salvador, 2009.

Velis Cabezas, Carlos Edgardo, Jesús Adalberto Arévalo Solórzano, Jaime Benjamín Yanes Reyes, and Rhina Franco. Incidence of the Previous English Knowledge of Fourth Year Students in the Bachelor of Arts in English Teaching Reflected in Their Academic Achievement Through Grades. San Salvador: Universidad de El Salvador, 2009.