  Magnetotransport has been investigated in high purity bismuth crystals in
static magnetic fields as high as 20 T and temperatures as low as 25 mK. This
high B/T ratio permits observation of pronounced Shubnikov-de Haas oscillations
over a wide field range and up to fields where most of the carriers are in the
lowest Landau level. For transport currents in the bisectrix or binary
directions and field in the perpendicular trigonal direction, we have observed
doublet splittings centered on each Shubnikov-de Haas oscillation. These
splittings exhibit a quadratic dependence on field and disappear before the
last oscillation. Our observations allow us to conclude unambiguously that
already when the Landau level index is as high as 2 the carriers are fully
polarized and that the g-factor for holes with the field in the trigonal
direction is 35.3(4).
