The earliest document containing Archimedes ‘work is Archimedes’ Sheepskin. In 1906, Danish professor Johan Ludvig Heiberg visited Constantinople and examined a 174-page sheepskin paper in the 13th century. Mountain Mew Pokemon shirt. He discovered that it was a sheepskin book, a text with words written on an erased old work. Sheepskin books were created by scraping ink from previous work and reusing them, this is a common practice in the Middle Ages because parchment is expensive. Old works on sheepskin were identified by scholars as X-century copies of the previously unknown treatises of Archimedes.