| Hermann Carl Eduard Biewend Mathilde and Hermann Koch with their Little Helena at Clausthal 1854, 7 July Daguerreotype, 1/4 plate 10.1 x 7.4 cm (image, sight) 10.7 x 8.1 cm National Gallery of Canada / Musée des beaux-arts du Canada Gift of Phyllis Lambert, Montreal, 1988, Accession number: 30601 LL/77513
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