  It has been derived that the Sommerfeld coefficient $\gamma $ as large as 25
J/K$^2$mol can be theoretically accounted for provided the charge f-electron
fluctuations are substantially suppressed. This result enables the
understanding of the heavy-fermion YbBiPt ($\gamma $ =8 J/K$^2$mol) as the spin
fluctuator and should stimulate the experimental specific-heat research at low
temperatures.
