2 - Policies Regarding CREDIBILITY of the World Heritage List
2.7 - Types of World Heritage properties
2.7.1 - Cultural, Natural and Mixed Properties
Decision of the World Heritage Committee 41 COM 9B
4. "[The World Heritage Committee] reiterates that due to the complexity of mixed site nominations and their evaluation, States Parties should ideally seek prior advice from IUCN and ICOMOS, if possible at least two years before a potential nomination is submitted, in compliance with Paragraph 122 of the Operational Guidelines."