@INPROCEEDINGS{Vilim2004CP,
  author = { Petr Vil{\'i}m and Roman Bart{\'a}k and Ond\v{r}ej {\v{C}}epek},
  title = {Unary Resource Constraint with Optional Activities},
  booktitle = {Principles and Pracitce of Constraint Programming - CP 2004, 10th
	International Confererence, CP 2004, Toronto, Canada},
  year = {2004},
  volume = {3258},
  series = {Lecture Notes in Computer Science},
  pages = {62--76},
  publisher = {Springer},
  isbn = {3-540-23241-9},
  url = {http://vilim.eu/petr/cp2004.pdf}
}