European Journal of Operational Research
European Journal of Operational Research > 1997 > 97 > 3 > 439-449
European Journal of Operational Research > 1997 > 98 > 1 > 19-36
European Journal of Operational Research > 1997 > 97 > 3 > 439-449
European Journal of Operational Research > 1997 > 98 > 1 > 19-36