Chandra/ACIS, Chandra/LETGS, INTEGRAL/IBIS-ISGRI, Suzaku/XIS, Suzaku/HXD-PIN, Swift/XRT,
Kirch et al. 2005, Proc. of SPIE "Crab: the standard x-ray candle with all (modern) x-ray satellites"
Weiskopf et al.2009, ApJ "On Calibrations Using the Crab Nebula and Models of the Nebular X-Ray Emission"
Tsujimoto et al. 2010, A&A "Cross-calibration of the X-ray Instruments onboard the Chandra, INTEGRAL, RXTE,
Suzaku, Swift, and XMM-Newton Observatories using G21.5--0.9"
Natalucci et al. A&A, in prep. "Cross-calibration of the X-ray instruments using the Crab nebula"