Link google scholar                 : https://scholar.google.com/ Link e resources perpusnas  : https://e-resources.perpusnas.go.id/ Link neliti                                    : https://www.neliti.com/id/ Link ERIC                                     : https://eric.ed.gov/ Link scimago                             : https://www.scimagojr.com/ Link mendeley dekstop          : https://www.mendeley.com/download-desktop-new/