Topology and its Applications
A finite CW complex X is said to be prime if for every Hurewicz fibration F → E → B with E homotopy equivalent to X, and B and F homotopically equivalent to finite CW complexes, either B or F is contractible. We show that the 3-plane complex Grassmannian Gn.3(C) is prime if n is odd.
Ferdinands, John, "Gn.3(C) is prime if n is odd" (1998). University Faculty Publications. 483.