@inproceedings{crossingthelinecrowdcountingbyinteger,
  title = {Crossing the Line: Crowd Counting by Integer Programming with Local Features},
  author = {Zheng Ma and Antoni B. Chan},
  year = {2013},
  booktitle = {CVPR 2013 6},
  url = {http://openaccess.thecvf.com/content_cvpr_2013/html/Ma_Crossing_the_Line_2013_CVPR_paper.html},
}