"Flatiron Building". National Historic Landmark summary listing. National Park Service. 2007-09-12. Archived from the original on 2013-03-14. Retrieved 2015-02-08.
"Flatiron Building". National Historic Landmark summary listing. National Park Service. 2007-09-12. Archived from the original on 2013-03-14. Retrieved 2015-02-08.