My guess is that you will find the necessary dependencies in the Stanford GraphBase:

http://www-cs-faculty.stanford.edu/~uno/sgb.html

If I remember correctly, the GraphBase source files start with the gb_ prefix (sorry, I'm ony phone so can't check).

Note: the Stanford GraphBase for me is an example of how a full blown library can be beautifully written in a literate style. Worth buying the hardcopy and reading it.

Did you use CWEAVE to convert the CWEB source to TeX? Then you can compile the TeX into a PDF that should be more readable than most source code out there.

http://www-cs-faculty.stanford.edu/~uno/cweb.html