A. G. Imana and Y. S. Nugroho, “UX (USER EXPERIENCE) EVALUATION OF THE OPENLEARNING SYSTEM AT UNIVERSITAS MUHAMMADIYAH SURAKARTA USING HEURISTIC EVALUATION AND USABILITY TESTING”, J. Tek. Inform. (JUTIF), vol. 4, no. 4, pp. 681-691, Aug. 2023.