Little boy, The arts of Japan's exploding subculture. Takashi Murakami, Yale University Press. 2005, ISBN 0-30-010285-2, page 135
Jrock, Ink.: A Concise Report On 40 Of The Biggest Rock Acts In Japan. Josephine Yun, Stone Bridge Press. 2005, ISBN 1-88-065695-7
Japan Pop!: Inside the World of Japanese Popular Culture. Timothy J. Craig (Editor), East Gate Book. 2000, ISBN 0-76-560560-0, page 82 (mentioned as a progressive group sound)
Crossing Over: Exploring Japanese Culture and Life Through English. Robert Long, Lulu.com. 2006, ISBN 1-41-162803-9, page 75 (Under 'relative clauses: who, which, that' --> "In the United States, I was shocked to learn that American's do not know about Mr.Children _________ is a group that is so popular here in Japan.")
Ecology of Language Acquisition. Jonathan Leather (Editor), Jet Van Dam (Editor), Springer. 2002, ISBN 1-40-201017-6, page 150 (Talks about a guy who used Mr.Children's name to gain popularity for his website (he called his website and himself Mr.Children while instead promoting another artist that was not Mr.Children on the site): "Here one finds the adoption of an iconic figure in the music industry as an identification badge for a J-pop fan".
In the Miso Soup. Ryū Murakami, Lulu.com. 2006, ISBN 1-41-162803-9, page 98, 102, 104, 109, 110, 112, 114, 115, 116, 119, 121, 131, 137 (This is a novel and in regards to Mr.Children, on page 98 a civil servant man was butchering a Mr.Children song during karaoke and later came to be known/called as Mr.Children for whatever reason. I suppose he was a big big fan of them)
Hip-hop Japan: Rap And the Paths of Cultural Globalization. Ian Condry, Duke University Press. 2006, ISBN 0-82-233892-0, page 105 (only mentions them very briefly)