During the past five years, a total of about 180 U-lines has been observed by the author and others in the 70-115 GHz region in the prominent molecular clouds Sgr B2 and Ori (KL). A program to identify the carriers of these lines has been undertaken. A computer code, incorporating nine different centrifugal distortion Hamiltonians, generates spectra of asymmetric rotors from given rotational and centrigugal-distortion constants. Spectra have been computed for ∼550 molecules that are considered potentially interesting astrophysically. Molecules were selected from Landolt-Bornstein Volumes IV (1967) and VI (1974) on Molecular Constants, and from the spectroscopic literature (1973 - present).