@inproceedings{Sperberg-McQueenHuitfeldt01,
  author	= {Sperberg-McQueen, C. M. and Huitfeldt, C.},
  title		= {GODDAG: a data structure for overlapping hierarchies},
  booktitle	= {Proceedings of PODDP'00 and DDEP'00},
  year		= {2001},
  address	= {New York}
}