P. Wahyuningsih, K. Wijaya, W. Trisunaryanti, A. Mara, and Suheryanto, “Synthesis and Application of Alumina Pillared Bentonite Catalyst for Esterification of Acetic Acid with Different Alcohols”, ajc, vol. 27, no. 4, pp. 1304–1308, Feb. 2015.