Legal Instruments Referenced Treaty of Neuilly

Treaty of Neuilly, (Nov. 27, 1919), peace treaty between Bulgaria and the victorious Allied powers after World War I that became effective Aug. 9, 1920.

Article 125
In addition to the payments mentioned in Article 121, Bulgaria undertakes to return, in accordance with the procedure to be laid down by the Inter-Allied Commission, objects of any nature and securities taken away, seized or sequestrated in the territory invaded in Greece, Roumania or Serbia, in cases in which it is possible to identify them in Bulgarian territory, except in the case of livestock, which shall be dealt with in accordance with Article 127.
For this purpose the Governments of Greece, Roumania and the Serb-Croat-Slovene State shall deliver to the Inter-Allied Commission within four months from the coming into force of the present Treaty lists of the objects and securities which they can prove to have been carried off from the invaded territories and which can be identified and found in Bulgarian territory. They will also give at the same time all information possible to assist in the discovery and identification of these articles.
The Bulgarian Government undertakes to facilitate by all means in its power the discovery of the said objects and securities, and to pass within three months from the coming into force of the present Treaty a law requiring all Bulgarian nationals to disclose all such objects and securities in their possession under penalty of being treated as receivers of stolen goods.

Article 126
Bulgaria undertakes to seek for and forthwith to return to Greece, Roumania and the Serb-Croat-Slovene State respectively any records or archives or any articles of archaeological, historic or artistic interest which have been taken away from the territories of those countries during the present war.
Any dispute between the Powers abovenamed and Bulgaria as to their ownership of any such articles shall be referred to an arbitrator to be appointed by the Inter-Allied Commission, and whose decision shall be final.

https://en.wikisource.org/wiki/Treaty_of_Neuilly/Part_VII