  Temperature dependence S(T) of the thermoelectric power of metallic systems
with cerium and ytterbium ions exhibits some characteristic features, which can
be used to classify these systems into distinct categories. The experimental
data are explained by the Kondo scattering in the presence of the crystal field
splitting and various shapes of S(T) are related to different Kondo scales that
characterize Ce and Yb ions at different temperatures. The low- and
high-temperature behaviors are calculated for different fixed point models and
the overall shape of S(T) is obtained by interpolation.
  At high temperatures, we use the Coqblin-Schrieffer model and calculate S(T)
by perturbation expansion with renormalized coupling constants. The
renormalization is performed by the 'poor man's scaling'.
  At low temperatures, we describe the dilute Ce and Yb alloys by an effective
spin-degenerate single-impurity Anderson model, and the stoichiometric
compounds by an effective spin-degenerate periodic Anderson model. The
parameters of these low-temperature models are such that their effective Kondo
scale coincides with the lowest Kondo scale of the Coqblin-Schrieffer model.
  The interpolation between the results obtained for the Anderson model and the
Coqblin-Schrieffer model explains the overall thermoelectric properties of most
Ce and Yb intermetallics.
