Some aspects of nonlinear discrete-time descriptor systems in economics / T. Fliegner, H. Nijmeijer and U. KottaDynamic disturbance decoupling for nonlinear discrete-time systems / T. Fliegner and H. NijmeijerRelative degrees and the policy lead in target control of dynamic economic systems / T. Fliegner and H. NijmeijerContributions to the control of non-linear discrete-time systems / Thomas FliegnerSolvability and right-inversion of implicit non-linear discrete-time systems / T. Fliegner, Ü. Kotta and H. Nijmeijer