ROSLI, S. N., OSMAN, M. H., & MAHYEDDIN, M. E. (2021). A Systematic Review: Optimization of Extracts Psidium Guajava L. By Using Ultrasound-Assisted with Soxhlet Extraction in Application of Food Preservation. Progress in Engineering Application and Technology, 2(1), 216-224. https://penerbit.uthm.edu.my/periodicals/index.php/peat/article/view/782