“Comparative Study of Combustible Species for 4-stroke Otto Cycle Combustion Motor and 6-stroke MUB-2 Cycle Combustion Motor with Fuel Pertamax: Studi Komparasi Kadar Combustible Species Motor Bakar 4 tak Siklus Otto dan Motor Bakar 6 tak Siklus MUB-2 Berbahanbakar Pertamax” (2021) Procedia of Engineering and Life Science, 1(2). doi:10.21070/pels.v1i2.1013.