  Rotating thin-shell-like sources for the stationary cylindrically symmetric
vacuum solutions (Lewis) are constructed and studied. It is found, by imposing
the non existence of timelike curves in the exterior of the shell, and that the
source satisfies the weak, dominant and strong energy conditions that the
parameters, commonly denoted by $a$ and $\sigma$, are restricted to $0 \le
\sigma \le 1/4$ when $a > 0$, or $1/4 \le \sigma \le 1/2$ when $a < 0$.
