Walker, John; Pickford, Andrew: 'Summary and future prospects for road pricing: open research areas, future work and conclusions' (Transportation, 2018), 'Road Pricing: Technologies, economics and acceptability', Chap. 21, pp. 547-567, DOI: 10.1049/PBTR008E_ch21
IET Digital Library, https://digital-library.theiet.org/;jsessionid=xk6j2dll7a1t.x-iet-live-01content/books/10.1049/pbtr008e_ch21