Ghaffari Moghaddam, M., et al. “Application of the Artificial Neural Network and Response Surface Methodology Models for Predicting the Enzymatic Synthesis of Betulinic Acid Ester: A Comparative Study”. Asian Journal of Chemistry, vol. 25, no. 1, Aug. 2012, pp. 301-5, doi:10.14233/ajchem.2013.13010.