"ČNS IFPI" (in Czech). Hitparáda – Digital Top 100 Oficiální. IFPI Czech Republic. Note: Select 40. týden 2021 in the date selector. Retrieved December 20, 2021.
hitparada.ifpicr.cz
"ČNS IFPI". IFPI ČR. Note: Select SK SINGLES DIGITAL TOP 100 and insert 202140 into search. Retrieved October 11, 2021.