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| Danish archeologist, Thorkild Ramskou, described the Sunstone theory in his books Solstenen, Primitiv Navigation i Norden før Kompasset., 1969 and Solkompasset, 1982. | |
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| Danish archeologist, Thorkild Ramskou, described the Sunstone theory in his books Solstenen, Primitiv Navigation i Norden før Kompasset., 1969 and Solkompasset, 1982. | |