  Recently the issue of EPR-like correlations in the mutual probability of
detecting neutrino together with accompanying charged lepton has received a new
impetus. In this paper we describe this effect using the propagators of the
particles involved in the Schwinger's parametric integral representation. We
find this description more simple and more suitable to the purpose than the
usual momentum-space analysis. We consider the cases of monochromatic neutrino
source, wave packet source, and neutrino creation in a localised space-time
region. In the latter case we note that the space-time oscillation amplitude
depends on the values of the neutrino masses, and becomes rather small for
large relative mass differences (mass hierarchy). We obtain the expressions for
the oscillation and coherence lengths in various circumstances. In the region
of overlap our results confirm those of Dolgov et al. [hep-ph/9703241].
