Home-made vacuum system for calculating the apparent density of solid materials - Rozali Annuar, Nur Hazirah; Ahmad Fadzillah, Nurrulhidayah; Karim, Ainul Hakimah; Ruslan, Nurun Najwa; Timmiati, Sharifah Najiha; Jalil, Aishah Abdul; Triwahyono, Sugeng (UTM Press, 2010)