A splitting theorem for open nonnegatively curved manifolds. Martin Strake — 1988 Manuscripta mathematica
Connection metrics of nonnegative curvature on vector bundles. Martin Strake; Gerard Walschap — 1990 Manuscripta mathematica
Rigidity of convex domains in manifolds with nonnegative Ricci and sectional curvature. Viktor Schroeder; Martin Strake — 1989 Commentarii mathematici Helvetici