CitNet Explorer is a citation network visualisation tool developed at Leiden University, available here http://www.citnetexplorer.nl/Home and documented here http://arxiv.org/abs/1404.5322.
In this fileset are some CitNet Explorer compatible files for one of the citation networks we used in our paper 'Transitive Reduction of citation networks', available here - http://arxiv.org/abs/1310.8224.pdf
We will hopefully be adding more information to this fileset (eg. author names) soon, but the current files are enough to start visualising the networks.