B.A. Williams, F. J. Kerr (21 December 1977). "H I observations of elliptical galaxies". The Astrophysical Journal. 222: 15. Bibcode:1978ApJ...222..800K. doi:10.1086/156199.
B.A. Williams, F. J. Kerr (21 December 1977). "H I observations of elliptical galaxies". The Astrophysical Journal. 222: 15. Bibcode:1978ApJ...222..800K. doi:10.1086/156199.