M. Ravindra and  R. Srinivasa Rao and  V. Shanmukha Naga Raju,  State Estimation Solution with Optimal Allocation of Phasor Measurement Units Considering Zero Injection Bus Modeling.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    October 2018, vol. 143(11). 788 - 793
    [viewed 19 May 2021]. Available from: https://publications.waset.org/pdf/10009739.