The Government publications selected from lists prepared by the Superintendent of Documents, and when requested from him, shall be distributed to depository libraries specifically designated by law and to libraries designated by Senators, Representatives, and the Resident Commissioner from Puerto Rico, by the Commissioner of the District of Columbia, and by the Governors of Guam, American Samoa, and the Virgin Islands, respectively. Additional libraries within areas served by Representatives or the Resident Commissioner from Puerto Rico may be designated by them to receive Government publications to the extent that the total number of libraries designated by them does not exceed two within each area. Not more than two additional libraries within a State may be designated by each Senator from the State. Before an additional library within a State, congressional district or the Commonwealth of Puerto Rico is designated as a depository for Government publications, the head of that library shall furnish his Senator, Representative, or the Resident Commissioner from Puerto Rico, as the case may be, with justification of the necessity for the additional designation. The justification, which shall also include a certification as to the need for the additional depository library designation, shall be signed by the head of every existing depository library within the congressional district or the Commonwealth of Puerto Rico or by the head of the library authority of the State or the Commonwealth of Puerto Rico, within which the additional depository library is to be located. The justification for additional depository library designations shall be transmitted to the Superintendent of Documents by the Senator, Representative, or the Resident Commissioner from Puerto Rico, as the case may be. The Commissioner of the District of Columbia may designate two depository libraries in the District of Columbia, the Governor of Guam and the Governor of American Samoa may each designate one depository library in Guam and American Samoa, respectively, and the Governor of the Virgin Islands may designate one depository library on the island of Saint Thomas and one on the island of Saint Croix.1