1. M. Amini, Tannaka-Krein duality for compact groupoids I, representation theory, Adv. Math., 214(1) (2007), 78–91.
2. W. R. Bloom and H. Heyer, Harmonic analysis of probability measures on hypergroups, De Gruyter, Berlin (1995).
3. J. B. Conway, A course in functional analysis, 2nd Edition, Springer, New York (1990).
4. C. F. Dunkl and D. E. Ramirez, A family of countably compact P*-hypergroups, Trans. Amer. Math. Soc., 202 (1975), 339–356.
5. G. B. Folland, A course in abstract harmonic analysis, CRC Press, London (1995).