 Each version bears many similarities to each other and to the "Pseudomonarchia Daemonum" and the "Ars Goetia", though they are far from identical.Johannes Trithemius mentions two separate works ("Liber" quoque "Officiorum", and "De Officiis Spirituum"), indicating that the text may have branched off by his time.Weyer, in his "Pseudomonarchia Daemonum", lists his source as "Liber officiorum spirituum."