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During World War II , aviation related activities included a factory dispersal site ( to minimize the risk of Luftwaffe bombing ) for Vickers-Armstrongs , who built and maintained Wellington bombers here .
 Luftwaffe, Vickers-Armstrongs
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Luftwaffe, Vickers-Armstrongs