[1] OHIO STATE UNIV, RADIO OBSERV, COLUMBUS, OH 43210 USA
[2] NATL RES COUNCIL CANADA, OTTAWA, ONTARIO, CANADA
[3] MULLARD RADIO ASTRON OBSERV, CAVENDISH LAB, CAMBRIDGE, ENGLAND
[4] ACAD SCI UKSSR, INST RADIO PHYS & ELECTR, KHARKOV, UKSSR
[5] QUEENS UNIV, DEPT PHYS, KINGSTON, ONTARIO, CANADA
[6] NATL RADIO ASTRON OBSERV, KITT PEAK, AZ USA
[7] UNIV TEXAS, RADIO ASTRON OBSERV, AUSTIN, TX 78712 USA
[8] MAX PLANCK INST RADIOASTRON, BONN, WEST GERMANY
[9] UNIV MACKENZIE, CTR RADIO ASTRON & ASTROFIS, SAO PAULO, BRAZIL
[10] YORK UNIV, CRESS DEPT PHYS, TORONTO, ONTARIO, CANADA
[11] STANFORD UNIV, RADIO ASTRON INST, STANFORD, CA 94305 USA
[12] CARNEGIE INST WASHINGTON, WASHINGTON, DC 20005 USA
[13] LICK OBSERV, SANTA CRUZ, CA 95060 USA