sentences:  That venture lasted less than two years.Blum operated the Irving Blum Gallery until his departure for New York City in 1972 where in partnership with Joseph Helman he opened the BlumHelman Gallery; he returned full-time to Los Angeles in 1998 as a private dealer.From 1965, the offices of the art magazine Artforum were situated above the gallery, before moving to New York City in 1967.