@misc{AlamBoraKarowetal.2011, author = {Rafik Alam and Shreemayee Bora and Michael Karow and Volker Mehrmann and Julio Moro}, title = {Perturbation theory for Hamiltonian matrices and the distance to bounded-realness}, institution = {Technische Universit{\"a}t Berlin}, type = {preprintmatheon}, year = {2011}, }