What should be in the center of Escher's painting 'Print Gallery'? Is there a single way to finish it? Can we find the original image before distortion? - Quora
Maurits Cornelis Escher (Dutch, 1898 - 1972) : Free Download, Borrow, and Streaming : Internet Archive
M.C. Escher: The Present, Now the Past | The Chapel
Belvedere (M. C. Escher) - Wikipedia
Drawing Hands, 1948 - M.C. Escher - WikiArt.org
M.C. Escher - 470 artworks - printmaking
The impossible world of MC Escher | Art and design | The Guardian