The Folio of 1165 - Novgorod

On the nature of Post-Mercurian Cults by Caesar ex Bonisagus: - Order of Hermes Lore Q10 - Details the mechanical methods of establishing such cults. Also contains some descriptions of less secretive mystery cults of the era. Though the information is nearly a century out of date.
On the liminal nature of Faeries by Beatrice ex Bonisagus (Q13 Faerie Lore tractatus detailing the tendency of faeries to manifest at boundaries between two states e.g. wilderness vs civilisation, shore and sea, life and death and so on.)
Mastery of Mastery by Phillipe ex Bonisagus (Q11 Rego Tractatus - a somewhat dry yet well structured text detailing how self-discipline and personal focus can be an aid to the use of Rego magic.)
Between Earth and Fire, a study on the nature of volcanoes by Stallus ex Bonisagus (Q 12 Tractatus, exp from studying this book is split evenly between Terram and Ignem due to the authors Elementalist training. )

The Greater Ager Belli Cr(Re)Im 15- Like the base spell (Ager Belli pg 58 Apprentices) but also produces sounds, but with a minor beneficial side effect that the resulting illusions automatically collide with each other and take damage based on interactions with other illusions. It is noted that when the Folio reached other covenants it coincided with a resurgence of the games with young magi and apprentices including a formalised league in the Rhine Tribunal at one point.
Wizard’s Reach Ignem (Lv 20) - Minor side benefit - Gives a +1 to any finesse rolls required by the primary spell.