"ČNS IFPI" (in Czech). Hitparáda – Radio Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – RADIO – TOP 100 and insert 200821 into search.
hitparadask.ifpicr.cz
"ČNS IFPI" (in Slovak). Hitparáda – Radio Top 100 Oficiálna. IFPI Czech Republic. Note: insert 200816 into search. Retrieved 1 December 2020.