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Twelve years after competing in her last Olympics , Tkach qualified for her second Russian team , as a 42-year-old , at the 2012 Summer Olympics in London , by placing second in the women 's trap from the 2011 European Shooting Championships in Belgrade , Serbia .
 Tkach, London, Belgrade , Serbia
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Tkach, London, Belgrade , Serbia