Christof Thoenes (1928–2018) studied art history in Berlin and Pavia, before completing his doctorate in Berlin. Thoenes was Honorary Professor in Hamburg and worked many years for the Bibliotheca Hertziana (Max-Planck-Institute) in Rome. He contributed to numerous publications on Italian art, particularly on architecture and architectural theory of the 15th to 18th centuries. Frank Zöllner wrote his doctoral thesis on motifs originating from Antiquity in the history of art and architecture of the Medieval and Renaissance periods (1987). He is also the author of a postdoctoral treatise on motion and expression in the art of Leonardo da Vinci, published in 2010. He has published numerous works on Renaissance art and art theory, and on 20th-century art. Since 1996 he has been Professor of Medieval and Modern Art at the University of Leipzig. For TASCHEN he has authored the XL monographs on Leonardo da Vinci and Michelangelo.