1. Experiments Relating to the Rendering of Gradation in Photogravure;Mills Cartwright;Phot. J., Dec.,1921
2. Tone Rendering by Half-Tone Processes;Bull,1928
3. Tone Reproduction in the ‘Half-Tone’ Photo-Engraving Process;Ives;J. Opt. Soc. Am.,1926
4. On the Theory of Tone Reproduction, with a Graphic Method for the Solution of Problems;Jones;J. FRANK. INST.,1920
5. General Considerations on the Photographic Reproduction of Luminosities;Abribat;Sci. et Ind. Photographique, 2,1935