Global 6 cm VLBI investigations of 0957+561 Campbell, R. M. ; Corey, B. E. ; Falco, E. E. ; Shapiro, I. I. ; Gorenstein, M. V. ; Elósegui, P. ; Marcaide, J. M. ; Alvi, K. Abstract Publication: Sub-arcsecond Radio Astronomy Pub Date: 1993 Bibcode: 1993sara.conf..131C