P^2

You might be looking for:


 * Groups of prime-square order (there are two of them) or classification of groups of prime-square order (explains why there are two of them)
 * Cyclic group of prime-square order
 * Elementary abelian group of prime-square order
 * Lie rings of prime-square order (there are three of them) or classification of Lie rings of prime-square order (explains why there are three of them)