Johnson, R. A. (1929). Modern geometry: An elementary treatise on the geometry of the triangle and the circle. Houghton Mifflin.
Lua i Stíl Chicago (17ú heag.)Johnson, Roger A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston: Houghton Mifflin, 1929.
Lua MLA (9ú heag.)Johnson, Roger A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Houghton Mifflin, 1929.
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