Ricardo Salem Zebulum Marco Aurélio Cavalcanti Pacheco Marley B. R. Vellasco Artificial Evolution of Active Filters: A Case Study. 66-75 1999 conf/eh/1999 Evolvable Hardware http://csdl.computer.org/comp/proceedings/eh/1999/0256/00/02560066abs.htm db/conf/eh/eh1999.html#ZebulumPV99