(a) For the purpose of this section- (1) "agency" has the meaning given it by section 5721 of this title; and (2) "appropriation" includes funds made available by statute under section 9104 of title 31. (b) When authorized by an appropriation or other statute, the head of an agency may procure by contract the temporary (not in excess of 1 year) or intermittent services of experts or consultants or an organization thereof, including stenographic reporting services. Services procured under this section