N⁎ → Nη′ decays from photoproduction of η′-mesons off protons. - Anisovich, A.V.; Burkert, V.; Collins, P.M.; Dugger, M.; Klempt, E.; Nikonov, V.A.; Ritchie, B.G.; Sarantsev, A.V.; Thoma, U. (Physics Letters B, 2017)