M. J. Leszka, Red., „Bulgarian-Byzantine Relations during the Reign of Symeon I the Great (893–927)”, w The Bulgarian State in 927-969. The Epoch of Tsar Peter I: No. XXXIV, Poland: Wydawnictwo Uniwersytetu Łódzkiego, 2018, s. 35–46. doi: 10.18778/8142-115-7.04.