6 books • 1 series
Book #7: Central European Olympiad, A: The Mathematical Duel
Book #19: Mathematical Nuggets From Austria: Selected Problems From The Styrian Mid-secondary School Mathematics Competitions
Book #25: Geometry In Our Three-dimensional World
Book #26: Creative Secondary School Mathematics: 125 Enrichment Units For Grades 7 To 12
Book #27: Mathematics: Its Historical Aspects, Wonders And Beyond