Comment 5 for bug 1328797

Nikolay, Those are raring packages which reach end-of-life 27 January, 2014.

old-releases.ubuntu.com is the right mirror to use at this time since raring has reached end-of-life. You may find other mirrors that still have raring available, as you did with us.archive.u.c, but the definitive source post-EOL is old-releases.u.c. Hope that helps clarify things.

You can substitute http://old-releases.ubuntu.com/ubuntu/ for http://security.ubuntu.com/ubuntu and
http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ (or http://<region>.ec2.archive.ubuntu.com/ubuntu/) in /etc/apt/sources.list.

Also a note about raring in particular due to a change of non-LTS lifespan starting with Saucy...
Raring is about 4 months past EOL so you'll want to think about upgrading. When planning please note that the non-LTS releases starting with Saucy[1] moved to a 9 month support cycle rather than the prior 18 months you have with Raring. This means that Saucy will EOL[2] in July 2014; at this point you might consider skipping Saucy and heading straight to Trusty if possible.

[1] https://wiki.ubuntu.com/SaucySalamander/ReleaseNotes#Support_lifespan
[2] https://wiki.ubuntu.com/Releases