On the G-spaces having an 𝒮 -G-CW-approximation by a G-CW-complex of finite G-type Martin Markl (1983) Commentationes Mathematicae Universitatis Carolinae
Orbit spaces of the hyperspace of a graph which are Hilbert cubes R. E. Heisey, J. E. West (1988) Colloquium Mathematicae