Siregar, Septoratno, Edy Soewono, Daniel Siregar, Satya A. Putra, and Yana Budicakrayana. 2013. “Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network”. Journal of Engineering and Technological Sciences 35 (1):23-43. https://doi.org/10.5614/itbj.eng.sci.2003.35.1.3.