“Suspension Bridge over the Niagara River.” ca. 1855-1856. Image courtesy Hirschl & Adler, New York. Image © 2019 Incollect.com. Fair use license. via https://www.incollect.com/listings/fine-art/paintings/joachim-ferdinand-richardt-suspension-bridge-over-the-niagara-river-293701
“Niagara Falls.” No date. Attributed to Richardt. Image © 2019 Sotheby’s. Fair use license. via http://www.sothebys.com/en/auctions/ecatalogue/2011/american-paintings-furniture-folk-art-and-silver-n08773/lot.305.html
“Underneath Niagara Falls.” 1862. Collection of the Metropolitan Museum of Art, New York. Cc0 license 1.0. via https://commons.wikimedia.org/wiki/File:Underneath_Niagara_Falls.jpg