Neighborhoods in line graphs Ľubomír Šoltés — 1990 Acta Universitatis Carolinae. Mathematica et Physica
Orientations of graphs minimizing the radius or the diameter Ľubomír Šoltés — 1986 Mathematica Slovaca
Two-radially maximal graphs with special centers Ferdinand Gliviak; Martin Knor; Ľubomír Šoltés — 1995 Mathematica Slovaca