Perturbation Theory for Dual Semigroups. I. The Sun-Reflexive Case. Ph. Clément; O. Diekmann; M. Gyllenberg; H.J.A.M. Heijmans; H.R. Thieme — 1987 Mathematische Annalen
A Hille-Yosida theorem for a class of weakly * continuous semigroups. Ph. Clément; O. Diekmann; M. Gyllenberg; H.J.A.M. Heijmans; H.R. Thieme — 1989 Semigroup forum