Hamann, Frederick W.; Barlow, T. A.; Chaffee, F. C.; Foltz, C. B.; Weymann, R. J. (2001-05-18). "High Resolution Spectra of Quasar AALs: 3C 191". arXiv:astro-ph/0105337.
Hamann, Frederick W.; Barlow, T. A.; Chaffee, F. C.; Foltz, C. B.; Weymann, R. J. (2001-03-20). "High-Resolution Keck Spectra of the Associated Absorption Lines in 3C 191". The Astrophysical Journal. 550 (1): 142–152. arXiv:astro-ph/0011030. doi:10.1086/319733. ISSN0004-637X.
Hamann, Frederick W.; Barlow, T. A.; Chaffee, F. C.; Foltz, C. B.; Weymann, R. J. (2001-03-20). "High-Resolution Keck Spectra of the Associated Absorption Lines in 3C 191". The Astrophysical Journal. 550 (1): 142–152. arXiv:astro-ph/0011030. doi:10.1086/319733. ISSN0004-637X.
Hamann, Frederick W.; Barlow, T. A.; Chaffee, F. C.; Foltz, C. B.; Weymann, R. J. (2001-03-20). "High-Resolution Keck Spectra of the Associated Absorption Lines in 3C 191". The Astrophysical Journal. 550 (1): 142–152. arXiv:astro-ph/0011030. doi:10.1086/319733. ISSN0004-637X.