@article{BDFP86, <br>AUTHOR = {Borodin, A. and Dolev, D. and  Fich, F. and Paul, W.J.},<br>TITLE = {Bounds for Width-Two Branching Programs},<br>VOLUME = {15}, <br>YEAR = {1986},<br>PAGES = {549--560}, <br>BOOKTITLE = {SIAM J. Comput. 1986}, <br>EE = {http://doi.acm.org/10.1145/800061.808736},<br>}