Original sentence: Article 20 contains the implicit possibility of allowing other referenda in the future by stating "All state authority is derived from the people.It shall be exercised by the people through elections and other votes and through specific legislative, executive and judicial bodies.The denial of referenda in other cases  was designed to avoid the kind of populism that allowed the rise of Hitler.Unlike the Weimar Constitution, the Basic Law only explicitly allows referenda on a single issue: changing borders of the Länder
Edited sentence: " These other votes – the words are to be understood meaning votes on legislatory issues – are, by now, common practice on the lewel of the länder.After referenda on reestablishing to länder borders as existed in the Weimar Republic all failed, this institution has not been used, as some little border changements can be done by state contract.Claims of extending this practice also to the federal lewel have an undisputed constitutional basis in the Article 20, being the general and inchangeable article on state structure.However, this could only be conferred by a constitutional amendment nevertheless.It shall be exercised by the people through elections and other votes (Abstimmungen) and through specific legislative, executive and judicial bodies.The denial of referenda in other cases was designed to avoid the kind of populism that allowed the rise of Hitler.Unlike the Weimar Constitution, the Basic Law only allows referenda, concerning the federal lewel of legislation, on a single issue: changing borders of the Länder.Yet Article 20 states that "All state authority is derived from the people