These are images used for testing various parts of the algoritm. The sources are
listed below:

* apatosaurus
  http://www.greatlittleminds.com/pages/word-search/dinosaur-names-word-search.html

* butterfly
  http://www.greatlittleminds.com/pages/word-search/butterfly-word-search.html

* cereal (mine)

* chemical elements
  https://www.thoughtco.com/element-word-search-puzzle-and-answer-607528

* dog
  http://imgur.com/Yr2tvnI

* easter egg
  http://eastercolouring.blogspot.com.au/2011/02/printable-easter-activity-sheets.html

* frozen
  http://momslifeboat.com/frozen-movie-review/

* the
  http://cnlohr.blogspot.com/2014/02/to-make-terrible-wordsearches.html

* autumn word find
  http://www.activityshelter.com/word-search-for-kids/

* triceratops
  http://www.greatlittleminds.com/pages/word-search/dinosaur-word-search.html

* amphibian
  https://www.exploringnature.org/db/view/3726
