Chaichan, Miqdam T., and Qahtan A. Abass. 2010. “Study of NOx Emissions of S.I. Engine Fueled With Different Kinds of Hydrocarbon Fuels and Hydrogen”. Al-Khwarizmi Engineering Journal 6 (2): 11-20. https://alkej.uobaghdad.edu.iq/index.php/alkej/article/view/485.