 Such are the "Formularium tabellionum" of Irnerius of Bologna in the 12th century, and the "Summa artis notariæ" of Ranieri of Perugia in the thirteenth; that of Salathiel of Bologna printed at Strasburg, in 1516, and the very popular one of Rolandino that went through many editions, beginning with the Turin edition of 1479.At the papal chancery, in general very faithful to its customs and its "style", after the reform of Innocent III many formularies and practical treatises appeared, none of them possessing an official value.The writings of Dietrich of Nieheim (an employee of the chancery in 1380), "De Stilo" and "Liber Cancellariæ", have been the subject of critical studies.