1. Alonso J. M. , Brady T. , Cooper D. , Ferlini V. , Lustig M. , Mihalik M. , Shapiro M. , Short H. , ‘Notes on word hyperbolic groups’, Group theory from a geometrical viewpoint (ed. H. Short ; World Scientific Publishing, River Edge, NJ, 1991) 3–63.
2. Some remarks on group actions on trees
3. Covering theory for graphs of groups
4. Bounding the complexity of simplicial group actions on trees
5. A combination theorem for negatively curved groups;Bestvina;J. Differential Geom.,1992