Abramowski A., Acero F., Aharonian F., Akhperjanian A.G, Anton G., Balzer A., Barnacka A., U. de Almeida B, Becherini Y., Becker J. et al..  2012.  The 2010 Very High Energy $\gamma$-Ray Flare and 10 Years of Multi-wavelength Observations of M 87}. The Astrophysical Journal. 746:151.

Aleksi? J., Antonelli L.A, Antoranz P., Backes M., Barrio J.A, Bastieri D., J. González B, Bednarek W., Berdyugin A., Berger K. et al..  2011.  MAGIC Discovery of Very High Energy Emission from the FSRQ PKS 1222+21. The Astrophysical Journal Letters. 730:L8.