Barus IRG, Simanjuntak MB. WHATSAPP GROUP AND GOOGLE CLASSROOM-BASED LEARNING MATERIALS IN ENGLISH CLASSES: STUDENTS’ PERCEPTIONS: (Study Case taken from College of Vocational Studies – IPB University). SELTICS [Internet]. 2020 Jun. 14 [cited 2026 Feb. 3];3(1):47-54. Available from: https://ejournals.umma.ac.id/index.php/seltics/article/view/552