Sudrajat, W. N. A., and E. R. Astuti. “Students’ Perceptions of the Use of TOEFL Preparation Online Course on the Test Performance: The Case of TOEFL Structure and Written Expression Test”. Humaniora, vol. 9, no. 3, Dec. 2018, pp. 275-82, doi:10.21512/humaniora.v9i3.4807.