Of course you can get those with `apt-get source` or just grab them from http://archive.ubuntu.com/ubuntu/pool/ http://archive.ubuntu.com/ubuntu/pool/ directly,

Of course you can get those with `apt-get source` or just grab them from http://archive.ubuntu.com/ubuntu/pool/ http://archive.ubuntu.com/ubuntu/pool/ directly, e.g. look for .orig.tar.xz, .dsc and .debian.tar.xz files in http://archive.ubuntu.com/ubuntu/pool/main/c/coreutils/ http://archive.ubuntu.com/ubuntu/pool/main/c/coreutils/. Not really sure who downloads all source in ISO form, seems rather pointless.