[1] FED TRADE COMMISS, WASHINGTON, DC 20580 USA
[2] ARIZONA STATE UNIV, TEMPE, AZ 85281 USA
[3] CATHOLIC UNIV LEUVEN, B-3000 LOUVAIN, BELGIUM
[4] UNIV ALBERTA, EDMONTON T6G 2M7, ALBERTA, CANADA
[5] EINDHOVEN UNIV TECHNOL, EINDHOVEN, NETHERLANDS
[6] AUSTRALIAN NATL UNIV, CANBERRA 2600, ACT, AUSTRALIA
[7] CENT MICHIGAN UNIV, MT PLEASANT, MI 48859 USA
[8] UNIV BERGEN, N-5014 BERGEN, NORWAY
[9] UNIV WISCONSIN, MADISON, WI 53706 USA
[10] UNIV TORONTO, TORONTO M5S 1A1, ONTARIO, CANADA
[11] UNIV CALGARY, CALGARY T2N 1N4, ALBERTA, CANADA
[12] MBLE RES LAB, BRUSSELS, BELGIUM
[13] STICHTING MATH CTR, AMSTERDAM, NETHERLANDS