LT UN-9, Leningrad
LT UN-9 was the abbreviation for the Printing House No. 9 of the Publishing and Printing Department of the Executive Committee of the Leningrad City Council. Research suggests the LT naming convention began during World War II and it was accorded to at least ten printers in Leningrad. For example, Printing House No. 1 (LT UN-1) was located at 57 Fontanka Embankment.
Lunacharsky A. V. (1941). Stat'i ob iskysstve. Moskva: Gosudarstvennoye izdatel'stvo izobrazitel'nogo iskusstva. (frontspiece of book indicates Printing House No. 1, Leningrad, 57 Fontanka Embankment)
leningradpobeda.ru/knigoizdanie (explanation of LT UN and its history)