Pratiwi, Henny. “MORPHOLOGICAL AND MECHANICAL PROPERTIES OF MT. KELUD VOLCANIC ASH REINFORCED POLYESTER AND EPOXY COMPOSITES”. Jurnal Teknik Mesin (Journal Of Mechanical Engineering), vol. 6, no. 2, Mar. 2017, pp. 108-13, doi:10.22441/jtm.v6i2.1189.