Currently I am working on plugin for Gephi platform that imports citations networks from Crossref resources.
Below you can watch it in action:
https://goo.gl/xJBFkr
This networks can further be analyzed by Gephi functions.
As we know Crossref is a valuable data store of metadata of scientific works.
What other open access valuable bibliographic data sources (in terms of completeness, quality, well defined web access) of scientific papers citations (that could be used for bibliometric, webometric and scientometric analysis) would you recommend?