  A new method of calculating unique values of ground-state shell corrections
for finite depth potentials is shown, which makes use of bound states only. It
is based on (i) a general formulation of extracting the smooth part from any
fluctuating quantity proposed by Strutinsky and Ivanjuk, (ii) a generalized
Strutinsky smoothing condition suggested recently by Vertse et al., and (iii)
the technique of the Lanczos $\sigma$ factors. Numerical results for some
spherical heavy nuclei ($^{132,154}$Sn, $^{180,208}$Pb and $^{298}$114) are
presented and compared to those obtained with the Green's function oscillator
expansion method.
