GPS radio sources: new optical observations and an updated master list A. Labiano, P. D. Barthel, C. P. O'Dea, W. H. de Vries, I. Pérez and S. A. Baum A&A, 463 1 (2007) 97-104 Published online: 20 November 2006 DOI: 10.1051/0004-6361:20066183