Boonmalai, Apichart, Jakmunee, Jaroon, AND Kritsunankul, Orawan. " Simultaneous Determination of Methanol and Ethanol Residues in Biodiesel by a Simple Headspace Single-Drop Microextraction and Gas Chromatography with Flame Ionization Detection" Naresuan University Journal: Science and Technology (NUJST) [Online], Volume 23 Number 3 (6 January 2016)