Lamberg-Allardt, Christel, Magritt Brustad, Haakon E. 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 March 2, 2021. https://foodandnutritionresearch.net/index.php/fnr/article/view/537.