Relational Reference Management Software? I'm looking for a reference management program to do three things:

(1) Manage references. There are plenty of solutions for this.

(2) Manage quotations. Similar to this question, whose suggestions were surprisingly lacking.

(3) Map relationships among references. Somewhat similar to the problem posed by this question. When doing research, I often (naturally) find new sources via reference from a current source. It would be extremely useful if my reference manager could look at all sources referenced by all of my current sources to reveal data gold mines like which sources in my library are referenced by other sources in my library, or (even better) what sources are referenced most frequently by all of the sources in my library.

For instance, if my library/collection contains sources A, B, C, D, E, then I want to see that A references B &amp; E, B references D &amp; E, and C references E. This information would also lend itself to useful descriptive statistics like "E is referenced by 3 sources in your library {A,B,C}" and even visual mapping of references.

With the vast array of reference management software available, I am amazed that I haven't found anything even close to this. Does anything like this currently exist?
As far as I know, there is nothing pre-canned for point (3). If you want to do it yourself, you'll need:


a way to retrieve automatically the references cited in each paper of your collection -- see here for some solutions. Note that an important part of this is giving each paper a unique identifier, something that is dealt with in literature databases.
a graph visualization/analysis tool. See for instance here.
Writing code -- sorry, there is no way around this. :(


EDIT: just noticed that this answer suggests a program called Google Scholar Citation Visualisation Tool -- give it a try!