349577
Peat extraction in the 17th and 18th century turned vast low-lying fen s into a collection of shallow , man-made lakes and bog s. Water lilies , reeds , swamps and wooded areas have developed spontaneously from the old peat canals ( trekgaten ) where the peat was extracted .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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