Gjerde, Hallvard, Elisabeth Leere Øiestad, and Asbjørg S. Christophersen. “Using Biological Samples in Epidemiological Research on Drugs of Abuse”. Norsk Epidemiologi 21, no. 1 (December 16, 2011). Accessed May 10, 2024. https://www.ntnu.no/ojs/index.php/norepid/article/view/1420.