  Mass- and wave-function renormalization is calculated to order $p^4$ in heavy
baryon chiral perturbation theory. Two different schemes used in the literature
are considered. Several technical issues like field redefinitions,
non-transformation of sources as well as subtleties related to the definition
of the baryon propagator are discussed. The nucleon axial-vector coupling
constant $g_A$ is calculated to order $p^4$ as an illustrative example.
