Barlow, T. A., Junkkarinen, V. T., Burbidge, E., Weymann, R. J., Morris, S. L., & Korista, K. T. (1992). Broad absorption-line time variability in the QSO CSO 203. Astrophysical Journal, 397, 81-87. https://doi.org/10.1086/171768