  We begin with an improvement to an extension result for subharmonic functions
of Blanchet et al. With the aid of this improvement we then give extension
results for subharmonic functions, for separately subharmonic functions, for
harmonic functions, for separately harmonic functions and for holomorphic
functions. Our results for holomorphic functions are related to Besicovitch's
and Shiffman's well-known extension results, at least in some sense. Moreover,
we recall another, slightly related and previous extension result for
holomorphic functions.
