of Incunabulum
Source: Webster's dictionaryEarly printed books, single sheets and images which were created before 1501 in Europe are known as incunables or incunabula. Source: Internet
Major collections The British Library 's Incunabula Short Title Catalogue now records over 29,000 titles, of which around 27,400 are incunabula editions (not all unique works). Source: Internet
Studies of incunabula began in the 17th century. Source: Internet
Very many incunabula are unique, but on average about 18 copies survive of each. Source: Internet