1. European Commission: The Guidelines for border management measures to protect health and ensure European Commission the availability of goods and essential services. Adopted by the European Commission on 16 Mar 2020. Brussels, Belgium (2020)
2. Mиниcтepcтвoтo нa тpaнcпopтa, инфopмaциoннитe тexнoлoгии и cъoбщeниятa: Плaн зa дeйcтвиe нa Peпyбликa Бългapия пo Cъoбщeниeтo нa Eвpoпeйcкaтa кoмиcия зa пpилaгaнeтo нa Зeлeнитe кopидopи oт Hacoкитe зa мepкитe зa yпpaвлeниeтo нa гpaницитe зa зaщитa нa здpaвeтo и ocигypявaнe нa нaличнocттa нa cтoки и ocнoвни ycлyги, C. 12. Coфия, Бългapия (2020) [in Bulgatian: Ministry of Transport, Information Technology and Communications: Action Plan of the Republic of Bulgaria under the Communication of the European Commission on the Implementation of Green Consumers from the Guidelines for Measures for Healthcare Management and Ensuring the Availability of Goods and Basic Services, p. 12. Sofia, Bulgaria (2020)]
3. Executive Agency “Automotive Administration”: Updated information on road traffic through the border checkpoints on the territory of the Republic of Bulgaria (2020). https://rta.government.bg/index.php?page=covid-19
4. Sommar, R., Woxenius, J.: Time perspectives on intermodal transport of consolidated cargo. Eur. J. Transp. Infrastruct. Res. 7, 163–182 (2007)
5. Macharis, C., Caris, A., Jourquin, B., Pekin, E.: A decision support framework for intermodal transport policy. Eur. Transp. Res. Rev. 3, 167–178 (2011)