1. Perturbation theory for dual semigroups
2. Clément, Ph., Diekmann, O., Gyllenberg, M., Heijmans, H. J.A.M. and Thieme, H. R. Perturbation theory for dual semigroups. II. Time-dependent perturbations in the sun-reflexive case. Proceedings of the Royal Society Edinburgh. Vol. 109A, pp.145–172
3. Clément, Ph., Diekmann, O., Gyllenberg, M., Heijmans, H. J.A.M. and Thieme, H. R. Perturbation theory for dual semigroups III. Nonlinear Lipschitz continuous perturbations in the sun reflexive case. Proceedings of the Conference on Volterra integro-differential equations in Banach spaces and applications, Edited by: Da Prato, G. and Iannelli, M. Vol. 190, pp.67–89Trento: Pitman Research Notes in Mathematics Series. 1987
4. A hille-yosida theorem for a class of weakly continuous semigroups