Regex:

  
NODE                     EXPLANATION
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  \[                       '['
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  \[                       '['
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  doi                      'doi'
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  \:                       ':'
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   *                       ' ' (0 or more times (matching the most
                           amount possible))
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  10                       '10'
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  \.                       '.'
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  [^]]+                    any character except: ']' (1 or more times
                           (matching the most amount possible))
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  \|                       '|'