"ČNS IFPI" (in Czech). Hitparáda – Radio Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – RADIO – TOP 100 and insert 201628 into search. สืบค้นเมื่อ July 18, 2016.
"ČNS IFPI" (in Czech). Hitparáda – Digital Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – SINGLES DIGITAL – TOP 100 and insert 201624 into search. สืบค้นเมื่อ May 24, 2016.
hitparadask.ifpicr.cz
"ČNS IFPI" (in Slovak). Hitparáda – Radio Top 100 Oficiálna. IFPI Czech Republic. Note: insert 201624 into search. สืบค้นเมื่อ July 3, 2016.
"ČNS IFPI" (in Slovak). Hitparáda – Singles Digital Top 100 Oficiálna. IFPI Czech Republic. Note: Select SINGLES DIGITAL - TOP 100 and insert 201626 into search. สืบค้นเมื่อ July 3, 2016.
Grein, Paul (June 19, 2017). "Chart Watch: Katy Perry's Disappointing Debut". Yahoo!. สืบค้นเมื่อ March 25, 2021. The Chainsmokers' "Don't Let Me Down" (featuring Daya) tops the 2 million mark in digital sales this week.