On the expansion of a function in terms of spherical harmonics in arbitrary dimensions. Kalf, Hubert — 1995 Bulletin of the Belgian Mathematical Society - Simon Stevin
Remarks on Some Dirichlet Type Results for Semibounded Sturm-Liouville Operators. Hubert Kalf — 1974 Mathematische Annalen
Self-Adjointness for Strongly Singular Potentials with a - |x|2 Fall-Off at Infinity. Hubert Kalf — 1973 Mathematische Zeitschrift
A Limit-Point Criterion for Separated Dirac Operators and a Little Known Result on Riccati's Equation. Hubert Kalf — 1972 Mathematische Zeitschrift
On the Essential Spectrum of Schrödinger Operators with Spherically Symmetric Potentials. Hubert Kalf; Rainer Hempel; Andreas M. Hinz — 1987 Mathematische Annalen