Giorgio Vasari 
Lives of the Most Eminent Painters, Sculptors, and Architects [PDF ebook] 
Translated From the Italian

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Ghiberti had already completed the north door, and was then working at that which was placed opposite to the cathedral.