@inproceedings{hills-2015-ase,
  author    = {Mark Hills},
  title     = "{Variable Feature Usage Patterns in PHP}",
  booktitle = {Proceedings of the 30th IEEE/ACM International Conference on Automated Software Engineering (ASE 2015)},
  year      = {2015},
  pages     = {563--573},
  publisher = {IEEE},
  doi       = {10.1109/ASE.2015.72},
}