Project Gutenberg should be added to the lyrics whitelist. This is mainly for audiobooks who's text is in the public domain. Project Gutenberg is an archive of public domain texts that serve as the "lyrics" for audiobooks/ prose works.

Links like http://www.gutenberg.org/ebooks/author/69 should be restricted to artists.

Links like http://www.gutenberg.org/ebooks/1661 should be restricted to release groups, works and possibly recordings. This link type should also be allowed as a download for free link as well on recordings and releases, as Project Gutenberg sometimes offers audiobook versions as well.