(en) Guy Ropars, Gabriel Gorre, Albert Le Floch, Jay Enoch et Vasudevan Lakshminarayanan, « A depolarizer as a possible precise sunstone for Viking navigation by polarized skylight », Proceedings of the Royal Society A : Mathematical, Physical and Engineering Sciences, The Royal Society, vol. 468, no 2139, , p. 671-684 (lire en ligne).