Webgraphy:

- http://audiotour.esbnyc.com/es/fun-hotspot/building-materials

- http://www.bing.com/images/search?q=plan+of+empire+state+building&view=detailv2&&id=8C67199F81C49C8F335E18C3582030C1291091C5&selectedIndex=1&ccid=RqaUK4jM&simid=608006017078396458&thid=OIP.M46a6942b88cc039b6a7bca55773a65bdo0&ajaxhist=0

- https://es.wikiarquitectura.com/index.php/Empire_State_Building

- https://es.wikipedia.org/wiki/Empire_State_Building