Mann 1906, p. 357: "And it is not unlikely that it was because John VIII. saw that Formosus might easily become the tool of designing men – or that at least the faction which had secured his interest might cloak their nefarious plans under the good name of the Bishop of Porto – that he forbade him to come to Rome again." Mann, Horace K. (1906). The Lives of the Popes In The Early Middle Ages. Vol. 3. London: Keegan Paul, Trench, Trübner & Co. Retrieved 1 February 2018.