https://pldml.icm.edu.pl/pldml/element/bwmeta1.element.bwnjournal-article-bcpv4i1p69bwm?q=bwmeta1.element.bwnjournal-number-bcp-1979-4-1;5&qt=CHILDREN-STATELESS
Approximation of double coset spaces - Banach Center Publications - Tom 4, Numer 1 (1979) - DML-PL...
double cosetapproximationspacesbanachcenter