I'm looking for the paper
Extensions of general algebras, S. Eilenberg, Ann. Soc. Polon. Math. 21, (1948). 125–134 (MR0026647 in Mathscinet)
It is supposedly hosted at the Digital Repository of Scientific Institutes (RCIN) here, but I cannot access it, although I have registered in the site.
Can someone locate another online copy, or send one to me?