Ubuntu 18.04 (Bionic Beaver) LTS

Schedule
https://wiki.ubuntu.com/BionicBeaver/ReleaseSchedule

ReleaseNotes
https://wiki.ubuntu.com/BionicBeaver/ReleaseNotes

Repository
echo "deb http://de.archive.ubuntu.com/ubuntu bionic-updates main restricted universe multiverse" > /etc/apt/sources.list.d/bionic-updates.list

Download
http://cdimage.ubuntu.com/releases/bionic/ - releases
http://releases.ubuntu.com/18.04/ - releases
32 bit Netboot CD
64 bit Netboot CD