1. BOBJ, http://cseweb.ucsd.edu/groups/tatami/bobj
2. The Coq proof assistant, http://coq.inria.fr
3. Isabelle, http://www.cl.cam.ac.uk/research/hvg/Isabelle
4. Aceto, L., Cimini, M., Ingolfsdottir, A.: A bisimulation-based method for proving the validity of equations in GSOS languages. To appear in Electr. Proc. Theor. Comput. Sci.
5. Bartels, F.: Generalised coinduction. Math. Struct. Comp. Sci. 13(2), 321–348 (2003)