Chairuddin Siregar and Irdian Ningsih, “THE INFLUENCE OF TEACHING MATERIALS DEVELOPMENT ON STUDENT UNDERSTANDING IN CLASS VII ISLAMIC RELIGIOUS EDUCATION SUBJECTS AT IT MIDDLE SCHOOL. AN-NAFIS TELUK MENGKUDU DISTRICT SERDANG BEDAGAI DISTRICT”, MORFAI, vol. 1, no. 2, pp. 488–496, Jan. 2022.