Smelyanskiy, Ruslan L.; Shalimov, Alexander: 'Introduction to SDN' (Computing, 2018), 'Big Data and Software Defined Networks', Chap. 1, pp. 3-25, DOI: 10.1049/PBPC015E_ch1
IET Digital Library, https://digital-library.theiet.org/;jsessionid=8lhp4ebndolcn.x-iet-live-01content/books/10.1049/pbpc015e_ch1