PWS-4
... that the PWS-4, a Polish sports aircraft built in 1928, was not developed beyond a single prototype?
... that the <b id="mweg"><a href="./PWS-4" id="mwew" rel="mw:WikiLink" title="PWS-4">PWS-4</a></b>, a Polish sports aircraft built in 1928, was not developed beyond a single prototype?