Béla Bartók's Viola Concerto, Sz. 120, BB 128 was written in July August 1945, in Saranac Lake, New York, while he was suffering from the terminal stages of leukemia. It was commissioned by William Primrose. Along with the Piano Concerto No. 3, it is his last work, and he left it incomplete at his death. The concerto was premiered in 1950 by the Minneapolis Symphony Orchestra with Antal Doráti conducting and William Primrose playing the solo part. The concerto has been completed three times: once by Bartók's friend and pupil, Tibor Serly (1949); once by Peter Bartók (son of the composer), Paul Neubauer, and Nelson Dellamaggiore (1995); and once by Csaba Erdelyi (copyright laws limit the availability of the Erdelyi version to retail stores in New Zealand and over the Internet).