met-medieval-art: Bifolium from a Gradual, Metropolitan Museum of Art: Medieval ArtBequest of Mrs. A
met-medieval-art:Bifolium from a Gradual, Metropolitan Museum of Art: Medieval ArtBequest of Mrs. A. M. Minturn, 1890Metropolitan Museum of Art, New York, NYMedium: Tempera, ink, and metal leaf on parchment -- source link