Sandhi Nugraheni, Anna Fitriawati, & 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). https://doi.org/10.55227/ijhet.v5i3.1192