Tumanggor, O. B., A. Aswani, and W. Syafitri. “Students’ Analyses Toward Grammatical Errors on Social Media’s Posts: Case Study in Politeknik Negeri Medan”. FOSTER: Journal of English Language Teaching, Vol. 2, no. 2, Apr. 2021, pp. 320-3, doi:10.24256/foster-jelt.v2i2.44.