Provided, however, that payment of such notes or bonds, both as to principal and interest, may be further secured by a pledge of any loan, grant or contribution from the federal government or any other source, in aid of any urban renewal projects of the Urban Renewal Authority under this article, and by a mortgage of any such urban renewal projects, or any part thereof, title to which is in the Urban Renewal Authority.
Okla. Stat. tit. 11, § 38-115