I am newbie and I have encountered installing an open source library integrated system. I have this error message below, please assist to to to avoid this from happening again;

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
debian-archive-keyring debian-keyring
0 to upgrade, 2 to newly install, 0 to remove and 123 not to upgrade.
Need to get 48.7 MB of archives.
After this operation, 55.7 MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
debian-archive-keyring debian-keyring
Install these packages without verification? [y/N] y
Err http://pg.archive.ubuntu.com/ubuntu/ trusty/universe debian-archive-keyring all 2012.4
404 Not Found
Err http://pg.archive.ubuntu.com/ubuntu/ trusty/universe debian-keyring all 2014.03.03
404 Not Found
E: Failed to fetch http://pg.archive.ubuntu.com/ubuntu/...2012.4_all.deb 404 Not Found

E: Failed to fetch http://pg.archive.ubuntu.com/ubuntu/....03.03_all.deb 404 Not Found

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Hello and welcome to the forum.

This means that a source is either down, no longer available or not entered correctly. To fix this, please see here.

As an aternative, you can download the files you were looking for here and here. These files are for Ubuntu 14.04, they may or may not work on other versions. Just download them to a location of your choice and install them by double clicking on them.

Regards...