V. Nagaraju and  Tapas Bapu. B. R and  Beryl J. Victor,  Single Port Overlay Cognitive Radio Using Reconfigurable Filtennas.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2014, vol. 95(11). 1819 - 1822
    [viewed 20 October 2019]. Available from: https://publications.waset.org/pdf/10000376.