Differential Geometry and Curvature
On the total curvature of knots
*On a relationship between the Betti numbers of a hypersurface and an integral of its Gaussian curvature
On total curvatures of closed space curves
On the existence of a connection with curvature zero
Eigenvalues of the Laplace operator on certain manifolds
A note on curvature and fundamental group
Problems in differential geometry
Curvatures of left invariant metrics on Lie groups
On deciding whether a surface is parabolic or hyperbolic
On fundamental groups of complete affinely flat manifolds
Algebraic Geometry and Topology
On the Betti numbers of real varieties
Isolated singularties defined by weighted homogeneous polynomials (with P. Orlik)
Isolated critical points of complex functions
Euclidean and non-Euclidean Geometry
A problem in cartography
Hilbert's problem 18: on crystallographic groups, fundamental domains, and on sphere packing
*How to compute volume in hyperbolic space
*Euler characteristic and finitely additive Steiner measures
Analytic proofs of the "Hair Ball Theorem" and the Brouwer Fixed Point Theorem
Hyperbolic geometry: the first 150 years
On the geometry of the Kepler problem
*The Schläfli differential equality