Almaini, O., Shanks, T., Boyle, B., Griffiths, R., Roche, N., Stewart, G., & Georgantopoulos, I. (1996). A deep ROSAT survey. XII. The X-ray spectra of faint ROSAT sources. Monthly Notices of the Royal Astronomical Society, 282, 295-303. https://doi.org/10.1093/mnras/282.1.295