On the representation of the modular group of order ½p (p2 – 1) as a group of linear substitutions on ½ (p – 1) symbols, ichen p is a prime of the form 4n + 3
William R. Burnside · Mathematical Proceedings of the Cambridge Philosophical Society · 1925
The actual form of the set of linear substitutions on 3 symbols, which gives a representation of the simple group of order 168, has been known for many years. In these Proceedings (vol. 20, pp. 247–9) I have determined the form of the set of linear substitutions on 5 symbols which gives a representation of the simple group of order 660.