The HARPS search for southern extra-solar planets - XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293
N. Astudillo-Defru, T. Forveille, X. Bonfils, D. Ségransan, F. Bouchy, X. Delfosse, C. Lovis, M. Mayor, F. Murgas, F. Pepe, N. C. Santos, S. Udry and A. Wünsche
