HST observations rule out the association between Cir X-1 and SNR G321.9-0.3R. P. Mignani, A. De Luca, P. A. Caraveo and I. F. MirabelA&A, 386 2 (2002) 487-491DOI: https://doi.org/10.1051/0004-6361:20020224
