Bibliography of non-Euclidean geometry, including the theory
of parallels, the foundations of geometry, and space of n
dimensions (1911).
- London Pub. by Harrison for the University of St. Andrews.
- https://archive.org/details/bibliographyofno00sommuoft
Avery, John Scales:
Videnskab og samfund, 2008 s. 46. 
Bonola, Roberto: Non-Euclidean Geometry. Dover Publications
Inc. 1958.
- https://archive.org/details/Non-euclideanGeometry
The thirteen books of Euclid's Elements.
- Cambridge: The University Press, 1908.
- https://archive.org/details/thirteenbookseu01heibgoog
- https://archive.org/details/thirteenbookseu02heibgoog
- https://archive.org/details/thirteenbookseu03heibgoog