1. W. I. Ervianto. Construction Project Manajemen, Manajemen Proyek Konstruksi. Yogyakarta: Andi. 2004.
2. H. Wilting and A. Hanemaaijer. “Share of raw material costs in total production costs”. PBL Netherlands Environmental Assesment Agency. Publication number 1506 (2014).
3. Y.H. Kwak. “Critical success factors in international development project managemen”. CIB 10th International Symposium Construction Innovation & Global Competitiveness. (2002). Available at http://home.gwu.edu/∼kwak/Kwak_CIB65_2002.pdf
4. An Introduction to Soil Concepts and the Role of Soils in Watershed Management