Nilsen, Trude, Carl Angell, og Liv Sissel Grønmo. «Mathematical Competencies and the Role of Mathematics in Physics Education: A Trend Analysis of TIMSS Advanced 1995 and 2008». Acta Didactica Norge 7, no. 1 (oktober 10, 2013): (Art. 6, 21 sider). åpnet oktober 23, 2021. https://journals.uio.no/adno/article/view/1113.