If you are posting a link to a reference on the internet, try to use doi's if they are available. Basically, a link with a doi should be permanent even if the article is moved in the future. Check out info on doi's here http://www.doi.org/
. I know that doi is not supported natively in Firefox, so you can use a proxy to bring up doi's with the following url: http://dx.doi.org/
. Simply place your doi at the end of this (check out the first post for an example).