請參閱
外部連結
- http://arxiv.org/ftp/physics/papers/0003/0003023.pdf （頁面存檔備份，存於網際網路檔案館）
- https://web.archive.org/web/20041213184419/http://www.bartleby.com/65/el/elemparTABLE.html
- http://www.pbs.org/wgbh/nova/elegant/part-flash.html（頁面存檔備份，存於網際網路檔案館）
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