Jamaludin, Jamaludin, et al. “STUDI EKSPERIMEN PENGGUNAAN VALVE HEAD MUSHROOM DAN VALVE HEAD TULIP PADA RECIPROCATING ENGINE TERHADAP PERFORMA ENGINE”. Jurnal Penelitian , vol. 5, no. 3, Nov. 2020, pp. 214-21, https://doi.org/10.46491/jp.v5i3.499.