Terrail, 2007 Harbison, 126–127 Ainsworth, 25–26 Kemperdick, 23 Stapleford, 19 Brown, 70 Woods-Marsden notes just two earlier examples, both of men: Castagno's Portrait of a Man and Mantegna's Portrait of Cardinal Ludovico Trevisan.
Terrail, 2007 Harbison, 126–127 Ainsworth, 25–26 Kemperdick, 23 Stapleford, 19 Brown, 70 Woods-Marsden finder blot to tidligere eksempler, begge af mænd: Castagnos Portræt af en mand og Mantegnas Portræt af kardinal Ludovico Trevisan.