Sandhi Nugraheni, Anna Fitriawati and Bagas Ardiyantoro 2026. Optimization And Stability Testing Of Avocado Leaf (*Persea americana*) Extract Soap Formulated With A Combination Of VCO, Palm Oil, And Olive Oil Using The Simplex Lattice Design Method. International Journal of Health Engineering and Technology. 5, 3 (Sep. 2026). DOI:https://doi.org/10.55227/ijhet.v5i3.1192.