--https://www.centos.org/
-CentOS-announce Info Page
--https://lists.centos.org/mailman/listinfo/centos-announce
-Red Hat Product Advisories - Red Hat Customer Portal
--https://access.redhat.com/security/security-updates/
-DNF Command Reference — dnf latest documentation
--https://dnf.readthedocs.io/en/latest/command_ref.html
-CentOS Mirror
--http://mirror.centos.org/
-->This directory tree contains current CentOS Linux and Stream releases.
-CentOS Vault
--http://vault.centos.org/
-Debuginfo Packages
--http://debuginfo.centos.org/
-Is it possible to limit yum so that it lists or installs only security updates? - Red Hat Customer Portal
--https://access.redhat.com/solutions/10021
-CentOS Linux 8
--http://www.nilab.info/wiki/CentOS_Linux_8.html
-CentOS Stream 8
--http://www.nilab.info/wiki/CentOS_Stream_8.html