Medicine
The association of Andrea and Giotto is historically documented by their joint work on the decoration of the bell tower. According to one tradition, the great painter from the Mugello carved some of the reliefs himself; in reality it is likely that the general programme, and perhaps some preparatory drawings, go back to him; the panels of the first tier (the others are later, reaching well into the fifteenth century) unmistakably reveal Andrea's style, even if he, having taken over the direction of the works of the cathedral in 1337, must have left ample room for the contributions of his assistants.
Bruno Balestrini (photograph), “Medicine”, work by Andrea Pisano, Gothic Sculpture, Florence, Museo dell'Opera del Duomo. Bruno Balestrini Photographic Archive, https://brunobalestrini.org/cita/sch00643/. Accessed [date accessed].