1. AV Security [n.d.]. Bugging Threats. AV Security. https://avsecurity.com/bugging-threats/ AV Security [n.d.]. Bugging Threats. AV Security. https://avsecurity.com/bugging-threats/
2. ThorLabs [n.d.]. PDA1000A2 - Si Switchable Gain Detector. ThorLabs. https://www.thorlabs.com/thorproduct.cfm?partnumber=PDA100A2 ThorLabs [n.d.]. PDA1000A2 - Si Switchable Gain Detector. ThorLabs. https://www.thorlabs.com/thorproduct.cfm?partnumber=PDA100A2
3. U.S.Department of Commerce Western Region Security Office 2001. Bugs and Other Eavesdropping Devices. U.S.Department of Commerce Western Region Security Office. https://www.wrc.noaa.gov/wrso/security_guide/intro-17.htm U.S.Department of Commerce Western Region Security Office 2001. Bugs and Other Eavesdropping Devices. U.S.Department of Commerce Western Region Security Office. https://www.wrc.noaa.gov/wrso/security_guide/intro-17.htm
4. Daily Mail 2016. Voice recorders in binders and secret meetings with undercover agents: How FBI penetrated Cold War-style Russian spy ring in New York City. Daily Mail. https://www.dailymail.co.uk/news/article-3484620/FBI-penetrated-New-York-based-Russian-spyring-using-hidden-recorders.html Daily Mail 2016. Voice recorders in binders and secret meetings with undercover agents: How FBI penetrated Cold War-style Russian spy ring in New York City. Daily Mail. https://www.dailymail.co.uk/news/article-3484620/FBI-penetrated-New-York-based-Russian-spyring-using-hidden-recorders.html
5. 2020. Shazam. https://www.shazam.com/ 2020. Shazam. https://www.shazam.com/