Peter Gnadig graduated as a physicist from Eoetvoes Lorand University (ELTE) in Budapest in 1971 and received his PhD in theoretical particle physics from the same university in 1980. He worked as a researcher in high energy physics and a lecturer in the Department of Atomic Physics at ELTE until he retired in 2010. Between 1985 and 2004, he was ... Read moreone of the leaders of the Hungarian team taking part in the International Physics Olympiad. Since 1989, he has been the physics editor for the Mathematical and Physical Journal for Secondary Schools. He is one of the authors of 200 Puzzling Physics Problems (Cambridge, 2001). Gyula Honyek graduated as a physicist from Eoetvoes Lorand University (ELTE) in Budapest in 1975 and received his PhD from the same university in 1977, after which he remained as a researcher and lecturer in the Department of General Physics. In 1985, he transferred to the teacher training school at ELTE, and was then mentor and teacher at Radnoti Grammar School, Budapest, until his retirement in 2011. Between 1986 and 2011, he was one of the leaders of the Hungarian team taking part in the International Physics Olympiad. He is one of the authors of 200 Puzzling Physics Problems (Cambridge, 2001). Mate Vigh graduated as a physicist from Eoetvoes Lorand University (ELTE) in 2010. He took part in the International Physics Olympiad as a contestant in 2003 and 2004. He has been one of the leaders and trainers of the Hungarian team since 2012. Ken F. Riley read Mathematics at the University of Cambridge and gained a PhD in theoretical and experimental nuclear physics, before following a research career in particle physics. He was also Senior Tutor at Clare College, Cambridge and a University Lecturer at the Cavendish Laboratory, where he taught physics and mathematics for over forty years. Amongst his other publications are the widely established mathematics textbook Mathematical Methods for Physics and Engineering, 3rd edition (2006) and the physics problems books Problems for Physics Students (1982) and 200 Puzzling Physics Problems (2001), all published by Cambridge University Press. Show Less