1. Cplex. Using the Cplex callable library and Cplex mixed integer library (1994). Cplex Inc.
2. Grötschel, M., Jünger, M., Reinelt, G.: On the acyclic subgraph polytope. Mathematical Programming, 33 (1985) 28–42
3. Grötschel, M., Pulleyblank, W.: Weakly bipartite graphs and the max-cut problem. Operations Research Letters, 1 (1981) 23–27
4. Hackbusch, W.: On the feedback vertex set problem for a planar graph. Technical report (1994). Institut für Informatik und Praktische Mathematik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
5. Jünger, M.: Polyhedral Combinatorics and the acyclic subdigraph problem., Research and exposition in mathematics 7 (1985). Heldermann Verlag, Berlin