He mentioned the letter of one of the members of Marini family to his agent Ciotti in which Marini asked the latter to get hime some "good old prints of Giulio Bonasone, Marc Antonion or other great masters..." He also quoted a letter from Count Fortunato which says "Use a little diligence to find some of the good prints of the able masters, such as Marc Antonio, Martino Rota, Giulio Bonasone, etc." These letters are evidence indicting the popularity of Bonasone's prints among collectors in the seventeenth century. Malvasia also pointed out Bonasone's weaknesses: "Although often great in execution of the principal parts of a composition," he wrote, Bonasone showed his lesser aptitude in the landscapes and the trees "which it is impossible to see worse executed." The comments by other art historians of Malvasia's time also showed the same opinion. Malvasia also analyzed Bonasone as a painter. He mentioned him with Lorenzo Sabbatini, who he considered to be Malvasia's teacher. Nonetheless, this relationship could not be backed up by analyzing the styles of Bonasone's paintings, which have all been lost. At the same time, Lorenzo Sabbatini was believed to live from 1530 to 1576 by most historians and therefore was not experienced enough to teach Bonasone. It is possible that Malvasia made a mistake about the relationship between the two artists but he still established the fact that Bonasone was a painter on top of his career as an engraver. Bonasone was covered in Adam von Bartsch's comprehensive study of sixteenth-century Italian engraving. Cumberland, in a second edition, accused Bartsch of copying his earlier catalogue. However, a careful analysis of the two works would reveal enough differences to demonstrate that the two art historians probably compiled their catalogues independently. Bartsch was able to analyze dated work to show chronological progression in Bonasone's techniques. He also pointed out the weaknesses of Bonasone's skills which had been previously mentioned in Malvasia's and Cumberland's comments. Bartsch tried to find reasons for these shortcomings, and suggested that Bonasone's interest was in content and composition, not in technique. He wanted to be regarded more as an artist than a technician. Bartsch appeared to suggest than the influence of Bonasone on other artists was more significant than the value of Bonasone's prints themselves.