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#Bombardment. - Art. 23.
Art. 23. Any air bombardment carried out for the purpose of enforcing requisitions in kind or payments of contributions in ready money, is forbidden.