I was looking for an article mimicing result of Pelczynski for $\ell_p$. I have found this one
Rodriguez-Salinas, B. (1994). On the Complemented Subspaces of $c_0(I)$ and $\ell_p(I)$ for $1 < p < \infty$, Atti Sem. Mat. Fis. Univ. Modena, 42, 399–402.
but I can't download it anywhere. Could someone provide me with this article or show main steps in that proofs.