Treaties, States Parties and Commentaries
Treaties and Documents
Geneva Conventions of 1949 and Additional Protocols, and their Commentaries
Historical Treaties and Documents
Rules concerning the Control of Wireless Telegraphy in Time of War and Air Warfare. Drafted by a Commission of Jurists at the Hague, December 1922 - February 1923.
Part II: Rules of Air Warfare#Chapter IV: Hostilities. - Art. 20.
Art. 20. In the event of an aircraft being disabled, the persons trying to escape by means of parachutes must not be attacked during their descent.