Nasrah, N.S.M., Mohd Zahari, M.A.K., Masngut, N. and Ariffin, H. 2017. Factorial experimental design for biobutanol production from oil palm frond (OPF) juice by Clostridium acetobutylicum ATCC 824. Chemical Engineering Research Bulletin. 19, (Sep. 2017), 36–42. DOI:https://doi.org/10.3329/cerb.v19i0.33774.