Objects that Cannot Be Taken Apart with Two Hands.
Oblique altitudes and bisectors
Observations sur les triangles rectangles en nombres entiers et les suites de Fibonacci
Odvození základních vzorců sférické trigonometrie pomocí některých pouček determinantních
On a certain triangle transformation and some of its applications.
On a functional equation arising from hyperbolic geometry.
On a general principle in geometry that leads to functional equations.
On a generalized stereographic projection. (Zur verallgemeinerten stereographischen Projektion.)
On a geometric inequality by J. Sándor.
On a system of equations related to bicentric polygons.
On an upper bound for the deviations from the mean value.
On Brocard points in the isotropic plane.
On Certain Construction of Rhombic Hexecontahedra
On continuous preservation of norms and areas.
On cyclic curves in the Euclidean n-space.
On distance preserving transformations of Euclidean-like planes over the rational fields.
On distance preserving transformations of Euclidean-like planes over the rational fields. (Short Communication).
On distance preserving transformations of lines in Euclidean three-space.
On Dominating Sequences in the Unit Disc.
On equations and properties concerning some classes of chordal polygons.