  In the recent paper Buchbinder, Kirillova and Pletnev presented formal
arguments concerning quantum equivalence of free massive antisymmetric tensor
fields of second and third rank to the free Proca theory and massive scalar
field with minimal coupling to gravity, respectively. We confirm this result
using explicit covariant calculations of non-local form factors based on the
heart-kernel technique, and discuss the discontinuity of quantum contributions
in the massless limit.
