瑞士畅销书作家埃里希·冯·丹尼肯认为它们是由受困的外星人建造的。
Bestselling Swiss author Erich von Daniken believed they were built by stranded extraterrestrials.
1969年，德国研究人员兼作家埃里希·冯·丹尼肯提出，这些线条是外星人为它们的飞机绘制的跑道。
One answer appeared in 1969, when the German researcher and writer Erich von Daniken proposed that the lines were drawn by extraterrestrials as runways for their aircraft.
德国联邦情报局专家埃里希·施密特-伊恩波恩发现了这份文件。 他曾发表过不少有关情报机构的著作和文章。
The files were discovered by BND expert Erich Schmidt-Eenboom, author of several books and papers on the spy agency.
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