@inproceedings{KPPY84,
AUTHOR = {Klawe, M. and Paul, W.J. and Pippenger, N. and Yannakakis, M.},
TITLE = {On Monotone Formulae with Restricted Depth},
YEAR = {1984},
PAGES = {480--487},
BOOKTITLE = {Proc. 16th ACM-STOC },
EE = {http://doi.acm.org/10.1145/800057.808717},
}