Salaries and expenses: For purchase and exchange of reference books, lawbooks, technical and scientific books, periodicals, and for expenses incurred in completing imperfect series; not to exceed $1,200 for newspapers; for dues, when authorized by the Secretary, for library membership in societies or associations which issue publications to members only or at a price to members lower than to subscribers who are not members; for salaries in the city of Washington and elsewhere; for official travel expenses, and for library fixtures, library cards, supplies, and for all other necessary expenses, $468,932, together with such amounts from other appropriations or authorizations as are provided in the schedules in the Budget for the fiscal year 1944 for such salaries and expenses, which several amounts or portions thereof, as may be determined by the Secretary, not exceeding a total of $750, shall be transferred to and made a part of this appropriation, of which total appropriation not to exceed $334,640, may be expended for personal services in the District of Columbia: Provided, however, That if the total amounts of such appropriations or authorizations for the fiscal year 1944 shall at any time exceed or fall below the amounts estimated, respectively, therefor in the Budget for 1944, the amounts transferred or to be transferred therefrom to this appropriation and the amount which may be expended for personal services in the District of Columbia shall be increased or decreased in such amounts as the Director of the Bureau of the Budget, after a hearing thereon with representatives of the Department, shall determine are appropriate to the requirements as changed by such reductions or increases in such appropriations or authorizations: Provided further, That the Secretary is authorized to make copies of bibliographies prepared by the Department library, microfilm and other photographic reproductions of books and other library materials in the Department and sell such bibliographies and reproductions at such prices (not less than estimated cost of furnishing same) as he may determine, the money received from such sales to be deposited in the Treasury to the credit of this appropriation.