“R. Berthon and M. Audibert patented a method of obtaining a virtual image by means of an anterior lens and prisms or mirrors. This idea was further improved upon in E.P. 17,023, 1913. In F.P. 458,040 Audibert proposed to use a negative front lens forming a virtual image and three positive lenses in rear to form coplanar images. T. Thorier stated that this arrangement considerably reduced parallax because the virtual image taken up by the positive lenses has but little depth of field.“
(Klein, Adrian Bernhard = Cornwell-Clyne (1940): Colour Cinematography. Boston: American Photographic Pub. Co.. 2nd revised edition, p. 304.)
Dr. N. (1937): Linsenraster. In: Film-Kurier, 183, 2.8.1937, Serie “Farb-Film-Fibel”. (in German)
Klein, Adrian Bernhard = Cornwell-Clyne (1940): Colour Cinematography. Boston: American Photographic Pub. Co.. 2nd revised edition, p. 304-305.
Rondelli, T. (1914): Lo stato attuale della cinematografia a colori. In: La Vita Cinematografica, 32–33, 30 Aug.–7 Sept. 1914, pp. 36, 41–43 published in Grifo, Marco (2006): Dal film colorato al cinema a colori. In: Michele Canosa, Giulia Carluccio and Federica Villa (eds.): Cinema muto italiano. Tecnica e tecnologia. Volume primo. Roma: Carocci, pp. 168–173, on pp. 170–171. (in Italian)