Askwith, E. H. (1917). A Course of Pure Geometry: The properties of the conic sections (Revised ed.). Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Askwith, Edward Harrison. A Course of Pure Geometry: The Properties of the Conic Sections. Revised ed. Cambridge: Cambridge University Press, 1917.
Lua MLA (9ú heag.)Askwith, Edward Harrison. A Course of Pure Geometry: The Properties of the Conic Sections. Revised ed. Cambridge University Press, 1917.
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