1. Akemann, C.A. and Walter, M.E., Unbounded negative definite functions,Can. J. Math.,13 (1981), 862–871.
2. Effros, E.G., Property Γ and inner amenability,Proc. Amer. Math. Soc.,47 (1975), 483–486.
3. Paschke, W.L., Inner amenability and conjugation operators,Proc. Amer. Math. Soc.,71 (1978), 117–118.
4. Pier, J.P., Quasi-invariance sur les localement compacts,Act. Math., Gauthier-Villars, 1982, Paris.
5. Pier, J.P., Amenable Locally Compact Groups, John Witley and Sons In., New York, 1984.