If you write a scientific paper describing research that made substantive use of this program, please cite the software appropriately, by mentioning the fashion in which this software was used, including the version number.
An appropriate citation would be:
Joris M. Mooij et al. (2010) "libDAI 0.2.5: A free/open source C++ library for Discrete Approximate Inference", http://www.libdai.org
or in BiBTeX format:
@misc{mooij2010libdai, author = "Joris M. Mooij et al.", title = "lib{DAI} 0.2.5: A free/open source {C}++ library for {D}iscrete {A}pproximate {I}nference", howpublished = "http://www.libdai.org/", year = 2010 }
Moreover, as a personal note, I would appreciate it to be informed about any publications using libDAI at joris dot mooij at libdai dot org.