Still, Martin; O'Brien, Kieran; Horne, Keith; Boroson, Bram; Titarchuk, Lev G.; Engle, Kimberly; Vrtilek, Saeqa Dil; Quaintrell, Hannah and Fiedler, Hauke
(2001).
Atmospheric reflection during an anomalous low state of Hercules X-1.Astrophysical Journal, 554(number 1, part 1)
pp. 352–361.