1. Betcke, M.M.: Iterative projection methods for symmetric nonlinear eigenvalue problems with applications. Ph.D. thesis, Institute of Numerical Simulation, Hamburg University of Technology (2007)
2. Betcke, M.M.: $${\sf QARPACK}$$ QARPACK : Quadratic Arnoldi Package. University College London (2011). http://www.cs.ucl.ac.uk/staff/M.Betcke/codes/qarpack
3. Betcke, M.M., Voss, H.: Restarting projection methods for rational eigenproblems arising in fluid-solid vibrations. Math. Model. Anal. 13, 171–182 (2008)
4. Betcke, T., Voss, H.: A Jacobi-Davidson-type projection method for nonlinear eigenvalue problems. Future Gen. Comput. Syst. 20(3), 363–372 (2004)
5. Betcke, T., Higham, N.J., Mehrmann, V., Schröder, C., Tisseur, F.: NLEVP: A collection of nonlinear eigenvalue problems. http://www.mims.manchester.ac.uk/research/numerical-analysis/nlevp.html