@inproceedings{ad2008,
 author = {B. A. Pearlmutter and
           J. M. Siskind},
 title = {Using Programming Language Theory to Make {AD} Sound and Efficient},
 booktitle = {Proceedings of the International Conference on Automatic
              Differentiation (AD)},
 pages = {79-90},
 location = {Bonn, Germany},
 day = {11--15},
 month = aug,
 year = 2008,
 url = {http://engineering.purdue.edu/~qobi/papers/ad2008.pdf}}