[0=ts_chart_artistname%3AKaty%20Perry&f[1]=ss_chart_search_title%3A%2AUnconditionally%2A&f[2]=tm_imprintlabel%3A%2ACapitol%2A&f[3]=itm_field_chart_id%3A-&f[4]=ss_bb_type%3Achart_item&label=Capitol&solrsort=sort_label%3Aasc&title=Unconditionally&type=1 Search results](англ.). Billboard. Дата обращения: 1 марта 2019.
"ČNS IFPI" (чешск.). Hitparáda – Radio Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – RADIO – TOP 100 and insert 201408 into search. Проверено 2014-02-24.
hitparadask.ifpicr.cz
"ČNS IFPI" (in Slovak). Hitparáda – Radio Top 100 Oficiálna. IFPI Czech Republic. Note: insert 201404 into search. Проверено 2014-02-24.