add function to extract references to library

Note that, this method is for auto-generated References and not Bibliography.

References can appear in different ways:

• Section: https://paste.ubuntu.com/p/y5mTmW7vgr/
  • article: https://en.wikipedia.org/wiki/Hans_Rehmann
• Section: https://paste.ubuntu.com/p/GpxXTFQg85/
  • article: https://en.wikipedia.org/wiki/Guignen
• Section: https://paste.ubuntu.com/p/zNmfWSKJsS/
  • article: https://en.wikipedia.org/wiki/Shuntaro_Hida