1. Directive 2003/87/EC of the european parliament and of the council of 13 octob 2003 establishing a scheme for greenhouse gas emission allowance trading within the cmmunity and amending council directive 96/61/EC,2003
2. CNG2020 - carbon neutrality growth for aviation,2020
3. Carbon offsetting and reduction scheme for international aviation,2016
4. The United States aviation climate action plan,2021
5. Carbon emissions calculator methodology,2018