"World's Tallest Towers: Timeline of all Skyscrapers Holding the Title of Tallest Building in the World From 1890 to the Present". skyscraper.org.
Accesat în 16 iunie 2008.  ^ a b c „World's Tallest Towers: Timeline of all Skyscrapers Holding the Title of Tallest Building in the World From 1890 to the Present”. skyscraper.org.