Fraser , Wesley T., Mark A. Sephton, Jonathan S. Watson, Stephen Self, Barry H. Lomax, David I. James, Charles H. Wellman, Terry V. Callaghan, and David J. Beerling. “UV-B Absorbing Pigments in Spores: Biochemical Responses to Shade in a High-Latitude Birch Forest and Implications for Sporopollenin-Based Proxies of past Environmental Change”. Polar Research00 (August 23, 2011). Accessed April 5, 2026. https://polarresearch.net/index.php/polar/article/view/3032.