@InProceedings{RWY97,
author={Alexander Razborov and Avi
Wigderson and Andrew Yao},
title={Read-once branching programs,
rectangular proofs of the pigeonhole
principle and transversal calculus},
crossref={STOC29},
booktitle={Proceedings of the 29th STOC},
pages={739-748},
year={1997},
}