BBC News - Device could make underwater objects appear invisible to sonar
http://www.bbc.com/news/science-environment-44058729
Scientists Didn't Invent a Star Trek 'Cloaking Device,' But What They Did Is Still Neat
https://gizmodo.com/scientists-didnt-invent-a-star-trek-cloaking-device-bu-1825917744
China and USA in race to submarine sonar stealth | NextBigFuture.com
https://www.nextbigfuture.com/2018/05/china-and-usa-in-race-to-submarine-sonar-stealth.html via @nextbigfuture