4 ACKNOWLEDGEMENTS
Grateful acknowledgement is made to the earlier scholarship on the Renaissance portraitists and to the owners and custodians of the illustra- tions; appreciative thanks are due to Sydney Anglo, Robert J. Knecht, Margaret M. McGowan, Rosalind K. Marshall, Edward B. Mayer, Mandy S. Mayer, Trevor Peach, Pauline M. Smith and the Librarians at the Bibliothèque Nationale, the British Library and the Cambridge University Library.