found: Rossini, G. The Rossini tenor [SR] p1988: label (the Ambrosian Singers) container (Ambrosian Choir)
found: New Grove: v. 11, p. 191 (Ambrosian Singers; choir founded in 1952 by John McCarthy, primarily to perform medieval and Renaissance works; in 1956, six members formed the Ambrosian Consort, specializing in Renaissance music; the Ambrosian Opera Chorus grew out of the original organization)
found: Music. Am., Int. dir. perform. arts, 1998: p. 722 (Ambrosian Opera Chorus; Ambrosian Singers [listed together])
found: Hartmann, T. de. Meetings with remarkable men [SR] 1979: label (Ambrosian Singers of London)