The Extra Thumb (sources)

• PRIMARY SOURCE: Post by user thfrbiddn1 in "Reddit, tell me your 'glitch in the matrix' stories," thread created by user superunhappyfuntime in the Reddit website, January 13, 2012. Online [in Internet Archive]: https://web.archive.org/web/20120118102510/http://www.reddit.com/r/AskReddit/comments/oeo0h/reddit_tell_me_your_glitch_in_the_matrix_stories/
• Historic posts of user thfrbiddn1 in Reddit website. Online: https://www.reddit.com/user/thfrbiddn1
• "Reddit thread: Tell me your 'Glitch in the Matrix' stories," by Robyn Wilder, article in the Slacktory website, posted 11-12-2012, viewed 8-8-2018. Online [in Internet Archive]: https://web.archive.org/web/20121115001947/http://slacktory.com/2012/11/reddit-thread-tell-me-your-glitch-in-the-matrix-stories/

Basic Story Repeaters:

• "13 Freaky Incidents That are Completely Unexplained," article in the Viral Nova Forum website, posted 10-14-2013, viewed 8-8-2018. Online: http://www.viralnova.com/unexplained-incidents/
• "Top 5 Mysterious Unexplained Photos Taken," article in the Nairaland Forum website, posted 7-21-2017, viewed 8-8-2018. Online: https://www.nairaland.com/3936712/top-5-mysterious-unexplained-photos
• "25 Mysterious and Creepy Photos that Might Never Be Explained," article in the GalleryRoulette website, posted ?, viewed 8-8-2018. Online: https://galleryroulette.com/creepy/25-mysterious-and-creepy-photos-that-might-never-be-explained/?subpage=5
• "10 Creepy and Mysterious Photos that Might Never Be Explained," article in the PolyTrendy website, posted 4-15-2018, viewed 8-8-2018. Online: https://www.polytrendy.com/10-mysterious-and-creepy-photos-that-might-never-be-explained/