Testing the correlations between ultra-high-energy cosmic rays and BL   Lac type objects with HiRes stereoscopic data
  Previously suggested correlations of BL Lac type objects with the arrival directions of the ultra-high-energy cosmic ray primaries are tested by making use of the HiRes stereoscopic data. The results of the study support the conclusion that BL Lacs may be the cosmic ray sources and suggest the presence of a small (a few percent) fraction of neutral primaries at E>10^{19} eV. 
D.S. Gorbunov, P.G. Tinyakov, I.I. Tkachev, S.V. Troitsky