TY - JOUR AU - Marek Sikora AU - Isaac Shlosman BT - The Astrophysical Journal DA - Jan-01-1989 DO - 10.1086/167036 PY - 1989 EP - 593 T2 - The Astrophysical Journal TI - Ultra-high-energy photons from active galactic nuclei - Theory UR - http://articles.adsabs.harvard.edu/full/1989ApJ...336..593S VL - 336 SN - 0004-637X ER -