Retrieved 25 July 2016. ↑ "XenialXerus/ReleaseNotes/UbuntuGNOME - Ubuntu Wiki". wiki.ubuntu.com. Retrieved 25 April 2016. ↑ "YakketyYak/ReleaseSchedule - Ubuntu Wiki". wiki.ubuntu.com. Retrieved 25 April 2016. ↑ "ZestyZapus/ReleaseSchedule - Ubuntu Wiki". wiki.ubuntu.com.