1.http://www.wealthwords.com/blog/evolution-of-crossword/
2.http://whatsnewinpublishing.com/how-puzzles-play-an-essential-role-in-reader-engagement/
3.http://whatsnewinpublishing.com/400000-people-now-subscribe-to-nyts-digital-crossword/
4.http://www.deseret.com/2008/2/22/20072031/crosswords-why-are-so-many-of-us-obsessed-with-puzzles-here-are-some-clues
5.http://www.theclintoncourier.net/2020/09/29/why-do-some-people-love-crosswords-so-much/
6.http://www.niemanlab.org/2021/03/the-new-yorker-leans-into-crossword-puzzles-online-and-now-in-print/
7.http://digiday.com/media/drive-daily-habits-customer-retention-publishers-turn-puzzles/
8.http://www.theguardian.com/gnm-press-office/2020/feb/11/the-guardian-launches-puzzles-a-new-app-for-crosswords-and-puzzles
9.http://www.insidehook.com/article/games/crossword-puzzles-print-media-new-yorker
10.http://techcrunch.com/2020/12/22/the-new-york-times-launches-an-ar-enabled-crossword-on-instagram/
11.http://www.wealthwords.com/blog/real-psychology-behind-crossword-puzzles/
12.http://www.smithsonianmag.com/arts-culture/crossword-became-american-pastime-180973558/
13.http://www.editorandpublisher.com/stories/consumer-view-to-the-business-pays-off-for-newsday,182452
14.http://www.washingtonpost.com/lifestyle/crossword-puzzle-diversity/2021/03/10/884828e0-753c-11eb-9537-496158cc5fd9_story.html