Agarwal, P. K.: 'Synchrophasors for improving the performance of power system' (Energy Engineering, 2017), 'Synchronized Phasor Measurements for Smart Grids', Chap. 1, pp. 1-28, DOI: 10.1049/PBPO097E_ch1 IET Digital Library, https://digital-library.theiet.org/;jsessionid=d59kfpylzzqd.x-iet-live-01content/books/10.1049/pbpo097e_ch1