@inbook{OB2007,
author = {A. Orriols-Puig and  E. Bernad\'o-Mansilla},
title = {The Class Imbalance Problem in UCS Classifier System: A Preliminary Study},
booktitle = {Advances at the frontier of LCS},
publisher = {Springer},
pages = {164--183},
year = {2007}
}