Nilsen, Trude, Carl Angell, og Liv Sissel Grønmo. 2013. «Mathematical Competencies and the Role of Mathematics in Physics Education: A Trend Analysis of TIMSS Advanced 1995 and 2008». Acta Didactica Norge 7 (1):(Art. 6, 21 sider). https://doi.org/10.5617/adno.1113.