There are no contracts proving that the mural project The Sky of Salamanca is definitively Fernando Gallego's. However, there is documentation from the rector Rodrigo Alvarez, requesting Fernando Gallego be hired to paint the library, since he had already worked for the cathedral on the Virgin of the Rose triptych. Documents also mention him by name in relation to the painting of the library coffers. Sky of Salamanca is located in the University of Salamanca's library ceiling. It reflects up-to-date astronomical knowledge, divided like an astrolabe and depicting constellations and planets. Source