Title: Let the Spacemen Beware!
Description: "To the men of the starship Quetzal their task seemed routine: to establish diplomatic relations and enter into trade negotiations with the people of a newly discovered planet. Since to all appearances the folk of Gwydion were the most thoroughly amiable in all the galaxy - words for such concepts as war, theft, anger, murder and jealousy did not even exist in their language - there could hardly be a problem. But as the season changed on Gwydion, so did the people..." - [Fantasy Fiction UK][1]


  [1]: http://www.fantasticfiction.co.uk/a/poul-anderson/let-spacemen-beware.htm