Pope Leo I — In the Basilica of Saint Paul Outside the Walls, Rome
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=42218683

Pope Sixtus III — In the Basilica of Saint Paul Outside the Walls, Rome
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=42218554

Pope Celestine I — In the Basilica of Saint Paul Outside the Walls, Rome
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=42218520

Basilica di Santa Maria Maggiore —
Photo Credit: By Pierre-Selim Huard - Self-photographed, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=49312166

Saint Peter Chrysologus — Diocesan Museum, Imola
Photo Credit: By School of Guercino - Public Domain, https://commons.wikimedia.org/w/index.php?curid=37448795

Page of Etymologiae — Carolingian manuscript (8th century), Brussels, Royal Library of Belgium
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=2261737

Isidore of Seville —
Photo Credit: By Bartolomé Esteban Murillo - Public Domain, https://commons.wikimedia.org/w/index.php?curid=131331

Saint Anselm, archbishop of Canterbury — A late 16th-century engraving
Photo Credit: By Unknown author - Public Domain, https://commons.wikimedia.org/w/index.php?curid=6663173

Saint Bonaventure —
Photo Credit: By François, Claude - Public Domain, https://commons.wikimedia.org/w/index.php?curid=5989525

Spline — Single knots at 1/3 and 2/3 establish a spline of three cubic polynomials meeting with C2 continuity. Triple knots at both ends of the interval ensure that the curve interpolates the end points
Photo Credit: By Garry R. Osgood - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4314548

Fürst Alexander Johann Cuza — Lithographie von Josef Kriehuber, 1861
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=38794754