Early mono vinyl releases had the format LRP-3xxx. Corresponding stereo releases (not available for all) would often have the catalog number style LST-7xxx with the same xxx value as the mono.
the label's official name was briefly changed to Liberty/United Records in 1978. unable to cover a loan from EMI, United Artists sold Liberty/United Records to EMI in 1979. In 1980, EMI dropped the United Artists name and revived the Liberty label for releases by artists who had been signed to UA. this latter incarnation of Liberty Records operated from 1980-1986, when it was deactivated and its artists assigned to other EMI labels.
the label was revived a second time in 1991, when EMI renamed its Capitol Nashville label to Liberty Records (wikipedia ref) before reverting to the former name in 1995. EMI reformatted the Liberty label name yet again in 2001, to focus on 'heritage acts', in the UK.