1. ATPC. African Trade Policy Centre of the Economic Comission for Africa (ECA) and the Department of Trade and Industry of the African Union Commission, 2020. African continental free trade area - questions and answers – updated. Accessed 7.2.2020, https://www.uneca.org/sites/default/files/uploaded-documents/ATPC/updated_q_a_21jan2020.pdf.
2. Aurubis, 2018. Geschäftsbericht und Magazin 2017/18. Accessed 12.12.2019, https://www.aurubis.com/binaries/content/assets/aurubisrelaunch/files/finanzberichte-de/2017-18/q4/geschaeftsbericht_aurubis_17_18.pdf.
3. Review of initiatives and methodologies to reduce CO2 emissions and climate change effects in ports;Azarkamand;Int. J. Environ. Res. Public Health,2020
4. The theory-generating expert interview: epistemological interest, forms of knowledge, interaction;Bogner,2009
5. Bremenports, 2020. Environmental report 2018: Ports of Bremen/Bremerhaven. Accessed 15.1.2020, https://bremenports.de/greenports/wp-content/uploads/sites/3/2017/04/PERS-Rezertifizierung_Report_2018_en.pdf.