Use of air space in the District of Columbia : hearings before the Subcommittee on Business and Commerce of the Committee on the District of Columbia, United States Senate, Ninetieth Congress, first session on S. 1245, to authorize the Commissioners of the District of Columbia to lease airspace above and below freeway rights-of-way within the District of Columbia, and for other purposes : S. 1246, to authorize the Commissioners of the District of Columbia to enter into leases for the rental of, or to use or permit the use of, public space in, on, over, and under the streets and alleys under their jurisdiction, other than freeways, and for other purposes : S. 1247, to authorize the Commissioners of the District of Columbia to fix and collect rents for the occupancy of space in, on, under, or over the streets of the District of Columbia, to authorize the closing of unused and unsafe vaults under said streets and the correction of dangerous conditions of vaults in or vault openings on public space, and for other purposes, July 25 and 27, 1967.