Соответствующая норма
Practice Relating to Rule 147. Reprisals against Protected Objects
Section A. Civilian objects in general
At the CDDH, Bulgaria stated that “his delegation favoured [an] amendment which sought to prohibit reprisals against civilian objects”. 
Bulgaria, Statement at the CDDH, Official Records, Vol. XIV, CDDH/III/SR.16, 10 February 1975, p. 134, § 31.