Kiriakidis, Peter, James William Decosta, et Antonio Sandu. 2011. « What is the effect of grade point average (GPA) on courses taken either face-to-face or online by undergraduate working adult students? ». Revista de Cercetare si Interventie Sociala 33 (juin): 7-26. https://www.rcis.ro/journal/article/view/338-what-is-the-effect-of-grade-point-average-gpa-on-courses.