; (2) assurances that funds received under this section will be used only to purchase materials for the library; (3) assurances that funds received under this section will be used to supplement, not supplant, other funds received by such library; and (4) an agreement to make available any financial records that the Office of Library Services may need for audit purposes. (b) Grant selection The Office of Library Services shall select the number of grant awards made under this section and the amount of each such award based upon economic need in accordance with regulations published by the Office.