Drake J.J., A. Brown, R.J. Patterer, P.W. Vedder, S. Bowyer, and E.F. Guinan, The Astrophysical Journal 421, L43 (1994).
Vedder P.W., R.J. Patterer, P. Jelinsky, A. Brown, and S. Bowyer, The Astrophysical Journal 414, L61 (1993).
Patterer R.J., P.W. Vedder, P. Jelinsky, A. Brown, and S. Bowyer, The Astrophysical Journal 414, L57 (1993).