  It is proved that quasi-exactly soluble potentials corresponding to an
oscillator with harmonic, quartic and sextic terms, for which the $n+1$ lowest
levels of a given parity can be determined exactly, may be approximated by WKB
equivalent potentials corresponding to deformed anharmonic oscillators of
SU$_q$(1,1) symmetry, which have been used for the description of vibrational
spectra of diatomic molecules. This connection allows for the immediate
approximate determination of the levels of the same parity lying above the
lowest $n+1$ known levels, as well as of all levels of the opposite parity.
Such connections are not possible in the cases of the q-deformed oscillator,
the Q-deformed oscillator, and the modified P\"oschl-Teller potential with
SU(1,1) symmetry.
