Press coverage
How did he do it? Building a backyard tunnel is no easy task
https://calgaryherald.com/news/local-news/how-did-he-do-it-building-a-backyard-tunnel-is-no-easy-task
Notable cases
Mole Man (2017) - IMDb
https://www.imdb.com/title/tt7441338/?ref_=ttnw_hdhttp://www.nottshistory.org.uk/portland1907/portland7.htm
http://www.nottshistory.org.uk/portland1907/portland7.htmThe Dead Duke, His Secret Wife, and the Missing Corpse: An Extraordinary Edwardian Case of Deception and Intrigue
https://books.google.com/books?id=MQVxBgAAQBAJ&pg=PT14&lpg=PT14&dq=John+Bentinck,+5th+Duke+of+Portland+obituaryCaves are not for claustrophobics
https://sduptownnews.com/caves-are-not-for-claustrophobics/Attention Required! | Cloudflare
https://www.sandiegoreader.com/news/1985/may/16/feature-digging-it-kensington/Forestiere Underground Gardens (Fresno, California)
http://historicfresno.org/nrhp/forest.htmSeymour Cray -- An Appreciation
http://www.cs.man.ac.uk/~toby/writing/PCW/cray.htm
Motivations
Insolite – Un original creuse un tunnel de 220 mètres sous sa maison
https://www.tdg.ch/suisse/faits-divers/original-creuse-tunnel-220-metres-maison/story/13133639Cavedigger: Inside Ra Paulette's luminous subterranean world
https://edition.cnn.com/style/article/cavedigger-new-mexico/index.htmlAttention Required! | Cloudflare
https://www.designingbuildings.co.uk/wiki/TunnellingLeanne (27) graaft tunnels om zich te ontspannen
https://www.ad.nl/amsterdam/leanne-27-graaft-tunnels-om-zich-te-ontspannen~a09e61d8/