On the nature of candidate luminous blue variables in M 33 J. S. Clark, N. Castro, M. Garcia, A. Herrero, F. Najarro, I. Negueruela, B. W. Ritchie and K. T. Smith A&A, 541 (2012) A146 Published online: 17 May 2012 DOI: 10.1051/0004-6361/201118440