| W. & F. Langenheim The Lord's Prayer - Containing 268 letters in a space the one thousand part of a square inch. and almost invisible by the naked eye. Made by W. F. Langenheim, Philadelphia n.d. Photomicrograph, slide, enlarged Private collection of Herbert C. McKay LL/48547 Photographs prepared by Herbert C. McKay and kindly provided by his grandson Maurice M. Greeson (19 June 2012).
| |