text: Alternative delimiters for [link definitions][link1] are allowed -- as of
  Markdown 1.0.2, I think. Hence, [this link][link2] and [this link][link3] work
  too.
  
  [link1]: http://daringfireball.net/projects/markdown/syntax#link "link syntax"
  [link2]: http://daringfireball.net/projects/markdown/syntax#link 'link syntax'
  [link3]: http://daringfireball.net/projects/markdown/syntax#link (link syntax)
  