References and the difference between Parts, Assemblies, and Drawings

I am only using the Document Manager. 

My Goal: Write a Console Applications that I give it a SolidWorks file name and gives me all the references of that file.

The Document manager help has a nice example entitled "Get External References Example" for ISwDMDocument15.  I modified that code to get the external references for parts and assemblies.  However, it does not seem to work for drawings. After some thought, do I have to traverse the drawing views and grab the reference from each drawing view to get a list of references for a drawing document?  Is there an easier way to handle drawing references?

My Console App:

SolidworksApi macros