Mario J. Micallef, John Douglas Moore, Minimal Two-Spheres and the Topology of Manifolds with Positive Curvature on Totally Isotropic Two-Planes, Annals of Mathematics, Second Series, Vol. 127, No. 1 (Jan., 1988), pp. 199-227
No takes yet. Share an insight, caveat, or question.
Micallef et al. (1988) studied this question.
Synapse has enriched one closely related paper. Consider it for comparative context: