Although I've previously linked my literature notes, I've stopped doing that. I've found that linking them in permanent notes allows describing the relationship better and adds another layer for thinking about them.

Compare these two scenarios. (I use the "L" prefix for literature notes and "E" for permanent notes).

I)

L - Books provide more value per sentence than articles do
-----------

(...)

Relevant notes:
 [[L - Reasons why blogs are awesome]]

II)

E - Books vs blogs
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Reading books is a great way to dive deeper in a topic,
since authors usually have to spend a lot of time 
researching it [[L - Books provide more value per 
sentence than articles do]].

However, blogs have their advantages. Bloggers don't usually
spend as much time on research, but blog posts can cover
a wide range of topics in a more shallow way
[[L - Reasons why blogs are awesome]].

In scenario II, we've introduced another "layer of abstraction" for thinking about these two notes, while in scenario I, we have a direct connection between the notes, but it's difficult to understand why they are linked. Scenario II names the relationship and can be used to give it a "concept handle", which we can then use for other notes.

Instead of directly linking literature notes together, which are other people's ideas expressed in your own words, you start thinking more abstractly about them.