van Leeuwen, Erik Jan Algorithms and Complexity, MPI for Informatics, Max Planck Society;
Mnich, M., & van Leeuwen, E. J. (2017). Polynomial Kernels for Deletion to Classes of Acyclic Digraphs. Discrete Optimization, 25, 48-76. doi:10.1016/j.disopt.2017.02.002.