deb http://deb.debian.org/debian stretch main contrib non-free
deb-src http://deb.debian.org/debian stretch main contrib non-free

deb http://deb.debian.org/debian-security/ stretch/updates main contrib non-free
deb-src http://deb.debian.org/debian-security/ stretch/updates main contrib non-free

deb http://deb.debian.org/debian stretch-updates main contrib non-free
deb-src http://deb.debian.org/debian stretch-updates main contrib non-free

# Nextcloud-client
# wget -q -O - http://download.opensuse.org/repositories/home:/ivaradi/Debian_9.0/Release.key | apt-key add
# apt update
# apt install nextcloud-client
deb http://download.opensuse.org/repositories/home:/ivaradi/Debian_9.0/ /
deb http://download.opensuse.org/repositories/home:/ivaradi/Debian_9.0_update/ /