Title: Boundary-sum irreducible finite order corks,
Abstract: We prove for any positive integer $n$ there exist boundary-sum irreducible
${\mathbb Z}_n$-corks with Stein structure. Here `boundary-sum irreducible'
means the manifold is indecomposable with respect to boundary-sum. We also
verify that some of the finite order corks admit hyperbolic boundary by HIKMOT.