Top 15 Secret Messages in Famous Songs From The Last 10 Years sources
http://whatculture.com/music/20-popular-songs-with-creepy-hidden-messages?page=3
https://www.thetoptens.com/famous-songs-with-hidden-messages-when-played-backward/page2.asp
http://www.cosmopolitan.com/entertainment/music/a12105658/taylor-swift-look-what-you-made-me-do-video-messages/
http://www.sheknows.com/entertainment/slideshow/3555/the-hidden-meaning-behind-pop-songs-including-hit-me-baby-one-more-time/m-i-a-s-paper-planes
http://www.cracked.com/article_20104_6-popular-songs-you-didnt-know-have-dark-hidden-messages.html
http://www.bbc.com/culture/story/20141003-the-hidden-messages-in-songs
http://mediaexposed.tumblr.com/post/8964092612/beyoncé-single-ladies-99-satanic-choreography
https://en.wikipedia.org/wiki/Secret_Messages
http://www.eeggs.com/items/30175.html
https://en.wikipedia.org/wiki/Pumped_Up_Kicks#Composition_and_inspiration
http://tonedeaf.com.au/16-hidden-tracks-messages-famous-songs/
http://www.cracked.com/article_18896_10-mind-blowing-easter-eggs-hidden-in-famous-albums.html
https://www.huffingtonpost.com/2014/05/09/reverse-speech-revolution_n_5288920.html
https://www.smithsonianmag.com/smart-news/the-fbi-investigated-the-song-louie-louie-for-two-years-78752777/
https://en.wikipedia.org/wiki/This_Land_Is_Your_Land#/media/File:Woody_Guthrie_2.jpg
https://www.thoughtco.com/nenas-99-luftballons-song-4076776
http://songmeanings.com/songs/view/18299/
http://www.rickandviv.net/index.php/2009/03/20/judas-kiss-with-intro-turned-around/
https://en.wikipedia.org/wiki/List_of_backmasked_messages