Spectroscopic confirmation of the optical identification of X-ray sources used to determine accurate positions for the anomalous X-ray pulsars 1E 2259+58.6 and 4U 0142+61M. van den Berg and F. VerbuntA&A, 368 2 (2001) 569-571DOI: https://doi.org/10.1051/0004-6361:20010023
