Descriptions from 1475 to 1568 attribute all of the tomb except for the figure of Faith to Donatello. Some modern sources reverse this dichotomy, attributing all of the tomb to Michelozzo with the exception of the gilded bronze effigy. Some sources credit Donatello only with the bronze effigy. According to Janson, of the marble work, only the "putti" can be attributed to "Donatello's own hand". Donatello's alleged deficiencies in casting or in architecture have been proposed as the reason for his partnership with Michelozzo, in addition to his busy schedule.