"ČNS IFPI" (in Czech). Hitparáda – Digital Top 100 Oficiální. IFPI Czech Republic. Note: Select 4. týden 2021 in the date selector. Retrieved February 1, 2021.
hitparada.ifpicr.cz
"ČNS IFPI". IFPI ČR. Note: Select SK SINGLES DIGITAL TOP 100 and insert 20214 into search. Archived from the original on April 1, 2019. Retrieved April 5, 2021.
"ČNS IFPI". IFPI ČR. Note: Select SK SINGLES DIGITAL TOP 100 and insert 20214 into search. Archived from the original on April 1, 2019. Retrieved April 5, 2021.