Nurestri Abd. Malek, S., H. Ibrahim, H. , S.L, L. , G.S, C. K.S, M. Mohd. Yusoff, and N. Azah Mohd. Ali. “Essential Oils of Zingiber Ottensii Valet. and Zingiber Zerumbet (L.) Sm. From Sabah, Malaysia”. Malaysian Journal of Science, vol. 24, no. 1, Jan. 2005, pp. 49-58, http://mjs.um.edu.my/index.php/MJS/article/view/8931.