Gamma ray sources observed with ARGO-YBJ

The air shower detector ARGO-YBJ is continuously monitoring the gamma ray sky in the declination band from −10° to +70° at energies . After ∼4 years of operation, the integrated sensitivity reached the level of ∼28% the Crab Nebula flux. In this work we present a summary of our observations concerning the Crab Nebula, the Cygnus region, the galactic source MGRO J1908+06, and the blazars Mrk421 and Mrk501.