@INPROCEEDINGS{Sivic2008,
  author = {Sivic, J. and Bryan C. Russell and Zisserman, A. and William
	T. Freeman and Alyosha A. Efros},
  title = {Unsupervised discovery of visual object class hierarchies},
  booktitle = {IEEE Conference on Computer Vision and Pattern Recognition},
  year = {2008},
}