Norma relacionada
Practice Relating to Rule 29. Medical Transports
Section B. Respect for and protection of medical aircraft
Sweden’s IHL Manual (1991) states that Articles 25–27 of the 1977 Additional Protocol I on the protection of medical aircraft have the status of customary law. 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section 2.2.3, p. 18.