Complex sentence: His art career resulted in loss of official approvement, therefore he had to make his exhibitions only in private households in Kiev, Odessa, Moskow and Leningrad (now St.Petersburg) from 1972 onwards.
Split into simpler sentences: His art career resulted in loss of official approvement. Therefore he had to make his exhibitions only in private households in Kiev, Odessa, Moskow and Leningrad (now St.Petersburg) from 1972 onwards.