Hjelmslev's Theorem: Geometry, Euclidean Plane Isometry, Parallel Postulate

Beckman Quarles Theorem: Geometry, Euclidean Space, Isometry

Lester's Theorem: Euclidean Plane, Geometry, Scalene Triangle

Parallel (Geometry): Geometry, Euclidean Space, Line (Mathematics), Plane Euclid

Arthur Cayley: Pure Mathematics, Projective Geometry, Cayley-Hamilton Theorem, Parallel Postulate, Cayley's Theorem