Elsheikh, Y.A. and Man, Z. and Bustam, M.A. and Yusup, S. and Wilfred, C.D. (2011) Brønsted imidazolium ionic liquids: Synthesis and comparison of their catalytic activities as pre-catalyst for biodiesel production through two stage process. Energy Conversion and Management, 52 (2). pp. 804-809. ISSN 01968904