https://www.nikon-image.com/enjoy/life/historynikkor/0040/index.html

https://gigazine.net/news/20190427-windows-10-data-capacity/

http://diamond.jp/articles/-/201183

https://www.itmedia.co.jp/news/spv/1904/27/news004_0.html

http://s-max.jp/archives/1770134.html

https://note.mu/tokuriki/n/nd9fe139224e0

https://www.gizmodo.jp/2019/04/ipad-mini-movie-review.html

https://smhn.info/201904-sony-mobile-xperia-has-withdrawn-from-latin-america-and-the-middle-east

https://smhn.info/201904-sharp-struggles-in-the-chinese-market

https://news.mynavi.jp/article/20190427-heiseisns1/

https://www.gizmodo.jp/2019/04/nikon-ricoh-canon-sony-camera.html