Add Debian sources list for Thailand

1. Go to edit sources.list

sudo vi /etc/apt/sourceslist

2. Add following line

deb http://linux.thai.net/debian unstable non-free contrib main
deb-src http://linux.thai.net/debian unstable non-free contrib main

deb http://debian.thaios.net/debian unstable non-free contrib main
deb-src http://debian.thaios.net/debian unstable non-free contrib main

deb http://ftp.coe.psu.ac.th/debian unstable non-free contrib main
deb-src http://ftp.coe.psu.ac.th/debian unstable non-free contrib main

3. Save and quit

4. Update your apt source

sudo apt-get update