See the Authors on Facebook
Welda Ayuansyah : https://www.facebook.com/welda.ayuansyah
A Labora Harahap : https://www.facebook.com/arvianilabora.harahap
Vivi Arianti : https://www.facebook.com/viviarianti27
M Wahyu Pratama : http://www.facebook.com/muhammad.wahyupratama.12