Blue box (English Wikipedia)

Wozniak, Steve (October 17, 2007). iWoz: Computer Geek to Cult Icon. W. W. Norton & Company. p. 110. ISBN 9780393066869 – via Internet Archive. bluebox subculture.
Whipple Jr., Spencer (June 1, 1975). "Inside Ma Bell". 73. pp. 68–80. Retrieved May 9, 2019 – via Internet Archive.

books.google.com (Global: 3^rd place; English: 3^rd place)

Wilson, E. Jan (December 6, 1998). Telecom and Network Security: Toll Fraud & Telabuse Update. TRI-Telecommunications Reports International, Incorporated. ISBN 9780938866091 – via Google Books.
Gitlin, Martin; Goldstein, Margaret J. (December 6, 2015). Cyber Attack. Twenty-First Century Books. ISBN 9781467725125 – via Google Books.
Shinder, Debra Littlejohn; Cross, Michael (July 21, 2008). Scene of the Cybercrime. Elsevier. ISBN 9780080486994 – via Google Books.
LLC, New York Media (June 6, 1977). "New York Magazine". New York Media, LLC – via Google Books.
Pursell, Carroll W. (December 6, 2007). Technology in Postwar America: A History. Columbia University Press. ISBN 9780231123044 – via Google Books.

doi.org (Global: 2^nd place; English: 2^nd place)

Breen, C.; Dahlbom, C. A. (1960), "Signaling Systems for Control of Telephone Switching" (PDF), Bell System Technical Journal, XXXIX (6): 1381–1444, doi:10.1002/j.1538-7305.1960.tb01611.x, The keyer relay M operates and releases from signals on the M lead and alternately removes or applies 2600 cycles to the transmit line of the facility. ... Table IV—Frequencies and Digit Codes for MF Pulsing: Digit 1: Frequencies 700 + 900 ...

explodingthephone.com (Global: low place; English: low place)

Phil Lapsley (2013). Exploding The Phone – Extra Goodies – Overseas Dialing. Grove Press. ISBN 978-0-8021-2061-8.

ghostarchive.org (Global: 64^th place; English: 28^th place)

Archived at Ghostarchive and the Wayback Machine: Sprint Phone Service commercial 1986 pin drop, retrieved March 16, 2021

historyofphonephreaking.com (Global: low place; English: low place)

Weaver, A.; Newell, N. A., "In-Band Single-Frequency Signaling" (PDF), Bell System Technical Journal

historyofphonephreaking.org (Global: low place; English: low place)

Breen, C.; Dahlbom, C. A. (1960), "Signaling Systems for Control of Telephone Switching" (PDF), Bell System Technical Journal, XXXIX (6): 1381–1444, doi:10.1002/j.1538-7305.1960.tb01611.x, The keyer relay M operates and releases from signals on the M lead and alternately removes or applies 2600 cycles to the transmit line of the facility. ... Table IV—Frequencies and Digit Codes for MF Pulsing: Digit 1: Frequencies 700 + 900 ...
Traffic Routing Guide, AT&T, 1977

itu.int (Global: 1,487^th place; English: 1,305^th place)

CCITT SS4 / ITU-T Q.120–139 https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Q.120-Q.139-198811-I!!PDF-E&type=items

jacobin.com (Global: 5,265^th place; English: 3,048^th place)

Day, Meagan (May 23, 2018). "When Ramparts Reigned". Jacobin. No. 29. pp. 52–56. ISSN 2470-6930. Retrieved December 6, 2022. p. 56.

latimes.com (Global: 32^nd place; English: 21^st place)

Stix, Harriet (May 14, 1986). "A UC Berkeley Degree Is Now the Apple of Steve Wozniak's Eye". Los Angeles Times. Retrieved January 5, 2015.

mit.edu (Global: 476^th place; English: 340^th place)

Sterling, Bruce (1993). "Part 2". The hacker crackdown: law and disorder on the electronic frontier ([2nd print.] ed.). New York: Bantam. ISBN 0-553-56370-X.

popularmechanics.com (Global: 2,521^st place; English: 1,621^st place)

Yan, Laura (October 22, 2019). "An Early Hacker Used a Cereal Box Whistle to Take Over Phone Lines". Popular Mechanics.

radioshackcatalogs.com (Global: low place; English: low place)

"1984 Radio Shack Catalog".

resource.org (Global: low place; English: 6,336^th place)

law.resource.org

UNITED STATES of America vs. Bernard CORNFIELD, dba Grayhall Inc, No. 76-3391, United States Court of Appeals, Ninth Circuit. October 27, 1977.

theatlantic.com (Global: 322^nd place; English: 198^th place)

Lapsley, Phil (February 20, 2013). "The Definitive Story of Steve Wozniak, Steve Jobs, and Phone Phreaking". The Atlantic.

todayifoundout.com (Global: low place; English: low place)

"Steve Jobs' First Business was Selling Blue Boxes that Allowed Users to Get Free Phone Service Illegally". October 6, 2012.

typepad.com (Global: 1,805^th place; English: 1,102^nd place)

hopp.typepad.com

Playing a tune for a telephone number, Popular Electronics, February 1950

web.archive.org (Global: 1^st place; English: 1^st place)

Archived at Ghostarchive and the Wayback Machine: Sprint Phone Service commercial 1986 pin drop, retrieved March 16, 2021
"NEW 'Off the Wall' ONLINE | 2600". Archived from the original on June 2, 2016. Retrieved May 31, 2016.

worldcat.org (Global: 4^th place; English: 4^th place)

search.worldcat.org

Day, Meagan (May 23, 2018). "When Ramparts Reigned". Jacobin. No. 29. pp. 52–56. ISSN 2470-6930. Retrieved December 6, 2022. p. 56.

youtube.com (Global: 13^th place; English: 14^th place)

AT&T, Speeding Speech, 1950
Archived at Ghostarchive and the Wayback Machine: Sprint Phone Service commercial 1986 pin drop, retrieved March 16, 2021

Blue box (English Wikipedia)

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historyofphonephreaking.com (Global: low place; English: low place)

historyofphonephreaking.org (Global: low place; English: low place)

itu.int (Global: 1,487th place; English: 1,305th place)

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popularmechanics.com (Global: 2,521st place; English: 1,621st place)

radioshackcatalogs.com (Global: low place; English: low place)

resource.org (Global: low place; English: 6,336th place)

law.resource.org

theatlantic.com (Global: 322nd place; English: 198th place)

todayifoundout.com (Global: low place; English: low place)

typepad.com (Global: 1,805th place; English: 1,102nd place)

hopp.typepad.com

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jacobin.com (Global: 5,265^th place; English: 3,048^th place)

latimes.com (Global: 32^nd place; English: 21^st place)

mit.edu (Global: 476^th place; English: 340^th place)

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resource.org (Global: low place; English: 6,336^th place)

theatlantic.com (Global: 322^nd place; English: 198^th place)

typepad.com (Global: 1,805^th place; English: 1,102^nd place)

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youtube.com (Global: 13^th place; English: 14^th place)