"Diagram of an 8 leaf gathering: Quaternion (8 folio or leaf gathering).
A quaternion is composed of 4 bifolios. Conjugate folios form a bifolio
at either end of a gathering or quire. So in the diagram above folios
1 and 8 which form a bifolio are conjugate folios."
History of Northern Renaissance Art
Dr. Allen Farber, Associate Professor
Tuesday, February 26: From Workshop to Chamber:
The Paris Book Industry of the Early Fifteenth Century
"Images for class" folder
An image from Publication, a Log24 post on the above date,