1. United Nations Department of Economic and Social Affairs, Population Division (2022). World population prospects 2022: summary of results. UN DESA/POP/2022/TR/NO. 3, https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/wpp2022_summary_of_results.pdf.
2. Ellen MacArthur Foundation & UN Environmental Programme. (2022). The global commitment 2022 progress report. https://ellenmacarthurfoundation.org/global-commitment-2022/overview.
3. Circular economy: a brief literature review (2015–2020);Arruda;Sustain. Oper. Comput.,2021
4. Food and Agriculture Organization of the United Nations. (Rome, 2022). FAO strategy on climate change. https://www.fao.org/3/cc2274en/cc2274en.pdf.
5. Co-digestion of wastewater treatment sewage sludge with various biowastes: a comparative study for the enhancement of biogas production;Mudzanani,2022