Соответствующая норма
Norway
Practice Relating to Rule 41. Export and Return of Cultural Property in Occupied Territory
During the diplomatic conference which led to the adoption of the 1954 Hague Convention for the Protection of Cultural Property, Norway proposed that “restitution cannot, however, be required later than twenty years after the object has got into the hands of the present holder, this holder having acted in good faith in acquiring it”. The proposal was not adopted by the conference. 
Jirí Toman, The Protection of Cultural Property in the Event of Armed Conflict, Dartmouth and UNESCO Publishing, Hants and Paris, 1996, p. 345.
Upon ratification of the 1954 Hague Protocol for the Protection of Cultural Property, Norway entered a reservation whereby “restitution of cultural property in accordance with the provisions of Sections I and II of the Protocol could not be required more than twenty years from the date on which the property in question had come into the possession of a holder acting in good faith”. In 1979, Norway withdrew this reservation. 
Jirí Toman, The Protection of Cultural Property in the Event of Armed Conflict, Dartmouth and UNESCO Publishing, Hants and Paris, 1996, p. 345.