Szigeti, C. i Borzán, A. (2012) „Extreme Outliers in the Database for Calculation of Ecological Footprint; The Problems of Grazing Land Footprint as Well as the Fishing Ground Footprint Calculation”, Zeszyty Naukowe SGGW w Warszawie - Problemy Rolnictwa Światowego, 12(3), s. 130–137. doi: 10.22630/PRS.2012.12.3.47.