Describing the beginning of Demon's affair with Marina, Van Veen (the narrator and main character in VN’s novel Ada, 1969) mentions Belokonsk, the Russian twin of ‘Whitehorse’ (city in N.W. Canada) on Demonia (Earth's twin planet also known as Antiterra):
Marina’s affair with Demon Veen started on his, her, and Daniel Veen’s birthday, January 5, 1868, when she was twenty-four and both Veens thirty.