DD-WRT Linux firmware comes to Linksys routers: "Open-source networking users will be happy to learn that Linksys finally made good on its promise to bring DD-WRT firmware to the Linksys router family." :
In-depth, hands-on review of Linksys WRT1900AC Wi-Fi router | TechHive
How to revert DD-WRT to factory firmware of a Linksys WRT1900ACS router – albertogonzalez.net
User Guide - WRT1900AC Dual Band Gigabit Wi-Fi Filter
User Guide - WRT1900AC Dual Band Gigabit Wi-Fi Filter
Amazon.com: Linksys Open Source Dual-Band Gigabit WiFi Wireless Router, Speeds up to (AC1900) 1.9Gbps - WRT1900ACS : Electronics
Amazon.com: Linksys WRT1900AC Dual-Band+ Wi-Fi Wireless Router with Gigabit & USB 3.0 Ports and eSATA, Smart Wi-Fi Enabled to Control Your Network from Anywhere : Electronics
Installing OpenWRT on a Linksys WRT1900ACS – David Simpson – deliver. iterate. repeat.