Wilkinson, W. T. Photo-Engraving, Photo-Etching, and Photo-Lithography in Line and Half-Tone: Also, Collotype and Heliotype [reproduction of a book published in 1923]. Berlin: NABU Press, 2010.

Wilkinson, W. T. Photo-Engraving, Photo-Etching, and Photo-Lithography in Line and Half-Tone: Also, Collotype and Heliotype [reproduction of a book published in 1923]. Berlin: NABU Press, 2010.