The restricted sumsets in finite abelian groups

Suppose that k 2 and A is a non-empty subset of a finite abelian group G with |G|>1. Then the cardinality of the restricted sumset k^ A: =\a₁++aₖ: \, a₁, , aₖ A, \ aᵢ aⱼ for i j\ is at least \p (G), k|A|-k²+1\, where p (G) denotes the least prime divisor of |G|.