installing sox and nano

While trying to install sox and nano, I get errors:

root <at> voyage:~# apt-get install sox
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package sox is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'sox' has no installation candidate
root <at> voyage:~# apt-get install nano
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package nano

What to do to get these software running in voyage?

Rüdiger