TIMSS 2015 international results in science
Martin, Michael O., Ina V. S. Mullis, Pierre Foy, and Martin Hooper. “TIMSS 2015 international results in science”, Chestnut Hill, Mass.: TIMSS & PIRLS International Study Center, Lynch School of Education, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:109282.