On Gnomons
On Groupoids Having a Linear Congruence Class Geometry.
On groups with root system of type .
On Havlíček-Tietze configuration in some non-Desarguesian planes
On hyperplanes and free subspaces of affine Klingenberg spaces.
On hyperplanes and free subspaces of affine Klingenberg spaces. (Summary).
On Incidence Matrices of Finite Projective and Affine Spaces.
On inflection points of some type of quartics with a single triple point
On inflection points of the plane quartic with two nodal and one flexnodal points
On Inscribed Circumscribed Conics.
On Involutorial Elations of Projective Planes.
On -chordal polygons.
On Lenz's problem on the independence of the axioms of affine space
On Lorentz-Minkowski geometry in real inner product spaces.
On mappings preserving a single Lorentz-Minkowski-distance in Hjelmslev's classical plane.
On Mathon's construction of maximal arcs in Desarguesian planes.
On M.D.S. codes, arcs in PG(n,q) with q even, and a solution of three fundamental problems of B. Segre.
On median point of the system of elements of -structure
On metric products
On minimum size blocking sets of external lines to a quadric in .