Christensen, J. H., M. Svensson, C. Strandhave, T. Madsen, and E. B. Schmidt. “N-3 Fatty Acids and Cardiac Autonomic Function in Humans”. Cellular and Molecular Biology, vol. 56, no. 1, Feb. 2010, pp. 131-9, https://mail.cellmolbiol.org/index.php/CMB/article/view/1017.