Triyani, Leni, et al. “THE PROBLEM OF TEACHERS DEVELOPING SHEET WORK OF STUDENTS (LKPD) HIGH SCHOOL BIOLOGY BASED SCIENTIFIC APPROACH ”. IJER - INDONESIAN JOURNAL OF EDUCATIONAL REVIEW, vol. 7, no. 02, Dec. 2020, pp. 27-32, https://journal.unj.ac.id/unj/index.php/ijer/article/view/21700.