  In the paper [1] we consider a new class, so-called, $G$-monogenic
(differentiable in the sense of Gateaux) quaternionic mappings. In the present
paper we introduce quaternionic $H$-monogenic (differentiable in the sense of
Hausdorff) mappings and establish the relation between $G$-monogenic and
$H$-monogenic mappings. The equivalence of different definitions of
$G$-monogenic mapping is proved.
