Schubring, Paul (1910): The Sistine Chapel. Rome: Frank & C. ASIN B00IK9KPD0. s. 41. Sitat: «(...) the man of sixty does not work with the same swiftness as before. And yet here he was not compelled to lie on his back, he had before him one single smooth vertical flat wall, softly bent forward, which he painted from the top to the bottom.»
