Cara M., E.S. Perlman, Y. Uchiyama, S. Jester, M. Georganopoulos, C.C. Cheung, R.M. Sambruna, W. Sparks, A. Martel, C.P. O'Dea, and S.A. Baum, in Aip (AIP, Fluno Center, Madison (Wisconsin), 2009), pp. 162-165.
Collinge M.J., W.N. Brandt, S. Kaspi, D.M. Crenshaw, M. Elvis, S.B. Kraemer, C.S. Reynolds, R.M. Sambruna, and B.J. Wills, The Astrophysical Journal 557, 2-17 (2001).