Rubacha, Jarosław. 2016. „Bulgarians and Bulgaria in the Last Quarter of the 19th Century in the Publications of Jan Grzegorzewski (culture, Population, Economy)”. Studia Z Dziejów Rosji I Europy Środkowo-Wschodniej 51 (1):23-46. https://doi.org/10.12775/SDR.2016.EN1.02.