http://linoxide.com/linux-how-to/dnf-commands-manage-rpm-linux/
http://www.tecmint.com/dnf-commands-for-fedora-rpm-package-management/
https://www.rootusers.com/25-useful-dnf-command-examples-for-package-management-in-linux/
http://dnf.readthedocs.io/en/latest/cli_vs_yum.html
https://fedoraproject.org/wiki/Features/DNF
https://media.readthedocs.org/pdf/dnf/latest/dnf.pdf
man dnf
man yum2dnf