1991 RJ2
1991 TB1
1991 TB2
1991 TT and 1991 TU
1991 Urey Prize Lecture: Physical evolution in the solar system - Present observations as a key to the past
1991 VA
1991 VB
1991 VB
1991 VE
1991 VG
1991 VG
1991 VG
1991 VG
1991 VH
1991 VH
1991 VH
1991 VH
1991 VK
1991 VK, 1991 VL, 1991 WA and 1991 XB
1991 VL