Intekhab Hussain, and M.G.Tiary. “An Ultra Wideband Bandpass Filter Using Stepped Impedance Resonators and DGS Structures”. International Journal of Computer Engineering in Research Trends, vol. 4, no. 5, May 2017, pp. 185-9, https://www.ijcert.org/index.php/ijcert/article/view/398.