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机译:On the coverings of closed orientable Euclidean manifolds G(2) and G(4)
Natl Res Univ, Higher Sch Econ, 20 Myasnitskaya Str, Moscow 101000, Russia;
Sobolev Inst Math, Novosibirsk, Russia;
Crystallographic group; Euclidean form; flat 3-manifold; nonequivalent coverings; platycosm;