1. NREL (National Renewable Energy Laboratory) (2018) Status and trends in the U.S. Voluntary green power market (2017 data).
https://www.nrel.gov/docs/fy19osti/72204.pdf
2. IRENA (International Renewable Energy Agency) (2018) Corporate sourcing of renewables: market and industry trends.
https://irena.org/-/media/Files/IRENA/Agency/Publication/2018/May/IRENA_Corporate_sourcing_2018.pdf
3. IRENA (International Renewable Energy Agency) (2019) Renewable energy market analysis: GCC 2019.
https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2019/Jan/IRENA_Market_Analysis_GCC_2019.pdf
4. Dagher L, Bird L, Heeter J (2017) Residential green power demand in the United States. Renew Energy 114:1062–1068
5. EPA (United States Environmental Protection Agency) (2019) History of voluntary markets.
https://www.epa.gov/greenpower/history-voluntary-markets