  Dronov and Kaplitzki showed that every complemented subspace of a nuclear
K\"othe space E with a regular basis of type ($d_1$) has a basis so, in
particular, solving the long standing problem whether any complemented subspace
of the space (s) of rapidly decreasing sequences has a basis. We present a
slightly modified version of their proof which shows that the range of every
closed-range operator in $E$ has a basis
