Wikisource URLs should be added to the sidebar in much the same way that Wikipedia and Wikidata URLs are added.

Examples:

On a person or group's page we'd see something like this:
http://en.wikisource.org/wiki/Author:Jane_Doe should display as "enwikisource: Author: Jane Doe" or just "enwikisource: Jane Doe". We may wish to drop the "author" prefix from the display. Or not.

For a work we'd see something like this:
http://en.wikisource.org/wiki/My_Great_Novel_Is_An_Audiobook_Cataloged_On_MusicBrainz would display as "enwikisource: My Great Novel Is An Audiobook Cataloged On MusicBrainz"

I'd also like to see the Wikisource icon next to the link as well.