A PL-manifold of nonnegative curvature homeomorphic to $S^2 \times S^2$ is a direct metric product (Preliminary version)

Some constructions related to H. Hopf’s Conjecture on product manifolds

J.P. Bourguignon · 1975

Earlier work this paper cites.

A vanishing theorem for piecewise constant curvature spaces

Jeff Cheeger · 1986

Earlier work this paper cites.

On some metrics on S 2 × S 2 {S}^{2}\times{S}^{2}

Masatake Kuranishi · 1993

Cited alongside, same era.

Polyhedral Kähler manifolds

Dmitri Panov · 2006

Cited alongside, same era.

Nonnegatively and positively curved manifolds, 2007

Burkhard Wilking · 2007

Later among the works it cites.