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@ebook{           Polya,
  Author        = "Polya, George",
  date-added    = "2020-04-10 11:05:14 +0200",
  date-modified = "2020-04-10 11:05:14 +0200",
  Keywords      = "popular science and favourite and done",
  Title         = "How to Solve It - A New Aspect of Mathematical Method",
  File          = "How to Solve It - A New Aspect of Mathematical Method - Polya (0)-1 (0) (0) - a - a - a.pdf",
  file-2        = "(Princeton Science Library) G. Polya-How to Solve It\_ A New Aspect of Mathematical Method-Princeton University Press (2004) (0) - a - a - a.epub"
}

@ebook{ Polya, Author = "Polya, George", date-added = "2020-04-10 11:05:14 +0200", date-modified = "2020-04-10 11:05:14 +0200", Keywords = "popular science and favourite and done", Title = "How to Solve It - A New Aspect of Mathematical Method", File = "How to Solve It - A New Aspect of Mathematical Method - Polya (0)-1 (0) (0) - a - a - a.pdf", file-2 = "(Princeton Science Library) G. Polya-How to Solve It_ A New Aspect of Mathematical Method-Princeton University Press (2004) (0) - a - a - a.epub" }