Direct injection of compressed natural gas (CNG) fuel for reciprocating piston internal combustion engine by Sahari, Barkawi, Aris, Ishak, Ahmadun, Fakhru'l-Razi, Ali, Yusoff, Abdullah, Shahrir, Hassan, Masjuki, Taha, Zahari, Abdullah, Luqman Chuah, Mariun, Norman, Abdullah, Muhd Adlan, Chelliah, V., Ku Hamid, Ku Halim, Musa, Md. Nor, Abd. Mutalib, Mohd Ibrahim, Abd. Aziz, Abd. Rashid, Ahmad, Mohd Fauzy