Biasi, Valeria. 2017. “Digital Learning and Virtual Educational Relationship. An Empirical Study on the Effectiveness of Audio-Video Systems in the on-Line Teaching for High School and University”. Formazione & Insegnamento 15 (1). Lecce-Brescia (IT):67-80. https://ojs.pensamultimedia.it/index.php/siref/article/view/2165.