Emission lines in the spectrum of the symbiotic star AG Draconis from 1997 to 2003L. Leedjärv, M. Burmeister, M. Mikołajewski, A. Puss, K. Annuk and C. GałanA&A, 415 1 (2004) 273-282DOI: https://doi.org/10.1051/0004-6361:20034224