Charles De Tolnay, Michelangelo: The tomb of Julius II, pg. 95-96: There is a discrepancy between the main and subcontracts of 1513 concerning the dimensions of the width and the height of the front. According to the main contract it is 20 palmi (4,40 meters) in width and 14 palmi (3,08 meters) in height; ... must have been clerical errors and have to be corrected on the basis of the subcontract into 30 and 17 palmi respectively