Helgason, Sigurdur, (1927-)

Groups and geometric analysis = integral geometry, invariant differential operators, and spherical functions / by: Helgason, Sigurdur, (1927-) (Language materials, printed)

Differential geometry and symmetric spaces by: Helgason, Sigurdur, (1927-) (Language materials, printed)

Differential geometry, Lie groups, and symmetric spaces by: Helgason, Sigurdur, (1927-) (Language materials, printed)