Masrukin, Y. E., N. Hassim, Z. Zakaria, N. S. A. S. Ali, and M. S. A. M Noh. “New Compact Dual-Band Bandpass Filter Using Stepped Impedance Resonator and U-Shaped Microstrip Structure”. Journal of Telecommunication, Electronic and Computer Engineering (JTEC), vol. 9, no. 2-8, Sept. 2017, pp. 99-102, https://jtec.utem.edu.my/jtec/article/view/2636.