1. V. Bouchitte and M. Habib, Invariants of ordered sets, in I. Rival (ed.): Algorithms and order (Reidel, Dordrecht) to appear.
2. A fast algorithm for the decomposition of graphs and posets;Buer;Math. Oper. Res.,1983
3. Minimizing bumps in linear extensions of ordered sets;Fishburn;Order,1986
4. A comparison of algorithms for minimizing bumps in linear extensions of partial orders;Gehrlein;Oper. Res. Letters,1987
5. M. Habib, R.H. Möhring and G. Steiner, Computing the bump number of ordered sets is easy, Report No. 87475 (University of Bonn, W. Germany).