Three XMM-Newton observations of the anomalous X-ray pulsar 1E 1048.1–5937: Long term variations in spectrum and pulsed fractionA. Tiengo, S. Mereghetti, R. Turolla, S. Zane, N. Rea, L. Stella and G. L. IsraelA&A, 437 3 (2005) 997-1005DOI: https://doi.org/10.1051/0004-6361:20052633
