@article{CHM2004,
 author = {David Maxwell Chickering and David Heckerman and Christopher Meek},
 title = {Large-Sample Learning of Bayesian Networks is NP-Hard},
 journal = {Journal of Machine Learning Research},
 volume = {5},
 year = {2004},
 issn = {1533-7928},
 pages = {1287--1330},
 publisher = {MIT Press},
 address = {Cambridge, MA, USA},
 }