New York Times: Grace Glueck, "The Fountainhead and Father of the Woolworth Building," December 29, 2000, accessed June 22, 2012 SIRIS: "Belgium, (sculpture)".
New York Times: Grace Glueck, „The Fountainhead and Father of the Woolworth Building“, 29. Dezember 2000, abgerufen am 22. Juni 2012 SIRIS: „Belgium, (sculpture)“.