In: Boček, Leo (editor); Horák, Karel (editor); Leischner, Pavel (editor); Moravčík, Jozef (editor); Šimša, Jaromír (editor); Töpfer, Pavel (editor): 43rd year of Mathematical Olympiad in high schools. Report on solving problems from the competition held in the school year 1993/1994. (Czech). Olomouc: Univerzita Palackého v Olomouci, 2016. 978-80-244-4927-7, pp. 78-80