Oodan, Antony P.; Ward, Keith E.; Savolaine, Catherine G.; Daneshmand, Mahmoud; Hoath, Peter: 'Telecommunications Quality of Service Management' (Telecommunications, 2003) DOI: 
IET Digital Library, https://digital-library.theiet.org/;jsessionid=8ffos9b7e3pjp.x-iet-live-01content/books/te/pbte048e