1. Renewable Power Generation Costs in 2020; Abu Dhabi, United Arab Emirateshttps://www.irena.org/publications/2021/Jun/Renewable-Power-Costs-in-2020
2. Global Energy Review 2021,2021
3. Statistical Review of World Energy 2020, BP 69th Editionhttps://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2020-full-report.pdf
4. The State Program on Use of Alternative and Renewable Energy Sources in Azerbaijanhttp://www.inogate.org/documents/AZ_2004_10_21_State_Program_on_Renewable_Energy_of_Azerbaijan_Republic.pdf
5. Cochrane Handbook for Systematic Reviews of Interventions;Higgins,2019