Smale, A., Done, C., Mushotzky, R., Weaver, K., Serlemitsos, P., Marshall, F., …Arnaud, K. (1993). Resolving the iron K line in Cygnus X-2 - an observation with BBXRT. Astrophysical Journal, 410, 796-802. https://doi.org/10.1086/172796