M-type giants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319 N. Masetti, M. Orlandini, E. Palazzi, L. Amati and F. Frontera A&A, 453 1 (2006) 295-299 Published online: 09 June 2006 DOI: 10.1051/0004-6361:20065025