Sphereland
Sphereland: A Fantasy About Curved Spaces and an Expanding Universe (Dutch: Bolland : een roman van gekromde ruimten en uitdijend heelal) is a 1957 novel by Dionys Burger, and is a sequel to Flatland, a novel by "A Square" (a pen name of Edwin Abbott Abbott). The novel expands upon the social and mathematical foundations on which Flatland is based.