1. Bel, G., & Calzada, J. (2009). Privatization and universal service obligations. Journal of Institutional and Theoretical Economics (JITE) /Zeitschrift Für Die Gesamte Staatswissenschaft, 165(4), 650–669. JSTOR, www.jstor.org/stable/40752782. Accessed 20 Oct 2020.
2. Belgian Institute for Postal Services and Telecommunications. (2021). Rapport de publication utilisateur final de services ... Belgian Institute for Postal Services and Telecommunications. Retrieved November 4, 2021, from https://www.bipt.be/file/cc73d96153bbd5448a56f19d925d05b1379c7f21/cd48a89e4c06f0148f9a115e44ceaa8bbd223d0f/Communication_utilisateurs_finals_services_postaux_belges.pdf.
3. Canada Post Corporation. (2010). Canadian postal service charter: Annual report 2009. Canada Post Corporation. www.canadapost.ca/cpo/mr/assets/pdf/aboutus/annualreport/Canadian_Postal_Service_Charter.pdf. Accessed 19 Nov 2020.
4. Canada Post Corporation. (2019). Service charter: Annual report 2018. Service Charter | Annual Report 2018 | Canada Post. www.canadapost.ca/cpc/en/our-company/about-us/financial-reports/2018-annual-report/corporate/service-charter.page. Accessed 19 Nov 2020.
5. Canada Post Corporation. (2020). Postal service charter: Annual Report 2019. Postal Service Charter | Annual Report 2019 | Canada Post. www.canadapost.ca/cpc/en/our-company/about-us/financial-reports/2019-annual-report/corporate/service-charter.page. Accessed 19 Nov 2020.