Yu, G., “The coarse Baum–Connes conjecture for spaces which admit a uniform embedding into Hilbert space.”, Invent. math., 139 (2000), 201–240 https://doi.org/10.1007/s002229900032
Ol’shanskii, A., “On the question of the existence of an invariant mean on a group”, Uspekhi Mat. Nauk, 35 (4) (1980), 199-200 https://www.mathnet.ru/rus/rm3788