Residents of Đà Nẵng begin using coupons with QR codes for shopping stockbot 0 446 2021.05.28 17:13 http://vietnamnews.vn/society/958234/residents-of-da-nang-begin-using-… + 15 https://vietnamnews.vn/rss/society.rss + 4 Residents in Đà Nẵng have started using coupons with QR codes when going to markets in a bid from city authorities to prevent large gatherings.