To examplify one of the criticisms, we included a link to a Wikipedia source. It is not 'definitive', but a reasonable link (more than most people would want to know), and anyone looking to learn more can continue their own search regarding the specifics. Our link checker brings up a 403 (forbidden request), but there is no problem with link functionality here. Could it affect any users? I could cite another source, but figure if the live link works for us then should simply work.

Also, on another page, we recommend a resource site that comes back with a 410 (the resource is no longer available). The link works fine to the directory. We could point up a directory, to the root directory, but would prefer to link straight to the resource. The live link is fully functional.?