Ridwan, W., and B. R. Trilaksono. “An LMI Approach to H∞ Performance Analysis of Continuous-Time Systems With Two Additive TimeVarying Delays”. Journal of Engineering and Technological Sciences, vol. 43, no. 2, Sept. 2013, pp. 127-38, doi:10.5614/itbj.eng.sci.2011.43.2.4.