@inproceedings{mdadams:equal,
  author = {Michael D. Adams and R. Kent Dybvig},
  title = {Efficient nondestructive equality checking for trees and graphs},
  booktitle = {Proceedings of the 13 ACM SIGPLAN International Conference on
    Functional Programming},
  pages = {179--188},
  year = {2008},
  texturl = "http://www.cs.indiana.edu/~dyb/pubs/equal.pdf",
  biburl = "http://www.cs.indiana.edu/~dyb/pubs/equal.bib",
  abstracturl = "http://www.cs.indiana.edu/~dyb/pubs/equal-abstract.html",
  annote = {An efficient algorithm for the nonterminating
     equal? R6RS procedure}
}