K. Letchumanan, N. H. Abdullah, M. M. Pisar, H. M. Ismail, R. Kadir, and A. Abdul-Aziz, “Application of Response Surface Methodology for the Optimization of the Extraction of Triterpenoid Saponins from Azadirachta excelsa Leaves”, Chemical Engineering Transactions, vol. 106, pp. 1159-1164, Dec. 2023.