@ARTICLE {6923,
author={A. Eira and J. M. Pedro and J. J. O.  Pires},
doi={10.1364/JOCN.4.000402},
journal={Journal of Optical Communications and Networking},
title={Optimized Design of Multistage Passive Optical Networks},
year={2012},
month={May},
volume={4},
number={5},
pages={402-411},
ISSN={1943-0620}
}