Joachim of Fiore. Enchiridion super Apocalypsim: Edited with notes and introduction. Studies and Texts, 78. Ed. Edward Kilian Burger. Toronto, Ontario, Canada: Pontifical Institute of Mediaeval Studies, 1986. 114 pp.
Joachim of Fiore (Joachim of Flora; Gioacchino da Fiore), d. 1135 – March 30, 1202, was a very influential theologian. His interpretation of Revelation caused a renewal of the ancient chiliasm, and he still has followers.
The Enchiridion was written 1194-1196 according to International Center for Joachimist Studies. Joachim wrote several other pieces on Revelation (see here).