Lamberg-Allardt, Christel, Magritt Brustad, Haakon Meyer, and Laufey Steingrimsdottir. “Vitamin D a Systematic Literature - Review for the 5th Edition of the Nordic Nutrition Recommendations”. Food & Nutrition Research00 (October 2, 2013). Accessed October 22, 2019. https://foodandnutritionresearch.net/index.php/fnr/article/view/537.