Two binary (integral type) Darboux transformations for the KdV hierarchy with
self-consistent sources are proposed. In contrast with the Darboux
transformation for the KdV hierarchy, one of the two binary Darboux
transformations provides non auto-B\"{a}cklund transformation between two n-th
KdV equations with self-consistent sources with different degrees. The formula
for the m-times repeated binary Darboux transformations are presented. This
enables us to construct the N-soliton solution for the KdV hierarchy with
self-consistent sources.Comment: 19 pages, LaTeX, no figures, to be published in Journal of
Mathematical Physic