A note on affine difference sets
\textit{H.-P. Ko} and \textit{O. K. Ray-Chaudhuri} [Discrete Math. 39, 37-58 (1982; Zbl 0484.05021)] have shown the following result: If there exists a cyclic affine difference set (for an affine plane) of even order \(n\neq 2\), then n is divisible by 4. We give a simple alternative proof for this result which also applies to abelian groups in general.
scientific article; zbMATH DE number 3908446