Auto-inserting source URL

It would be great to have the following feature:
when copy-pasting from Web the source URL would be inserted at the end of copied html text (or pictures). Then if I press Undo then this source URL would be removed. If I press UNDO twice then all the copy/paste action will be undone. Exactly the same feature is present in Evernote (I’m sorry to say, but I switched to Evernote because of this only feature because I do a lot of web research and saving source URL manually each time was a real pain for me).

Thank you in advance!