A broad absorption feature in the X-ray spectrum of the isolated neutron star RBS1223 (1RXS J130848.6+212708)F. Haberl, A. D. Schwope, V. Hambaryan, G. Hasinger and C. MotchA&A, 403 1 (2003) L19-L23DOI: https://doi.org/10.1051/0004-6361:20030450
