Research work on the "Book of the Dead" has always posed technical difficulties thanks to the need to copy very long hieroglyphic texts. Initially, these were copied out by hand, with the assistance either of tracing paper or a camera lucida. In the mid-19th century, hieroglyphic fonts became available and made lithographic reproduction of manuscripts more feasible. In the present day, hieroglyphics can be rendered in desktop publishing software and this, combined with digital print technology, means that the costs of publishing a "Book of the Dead" may be considerably reduced. However, a very large amount of the source material in museums around the world remains unpublished.