On August 21, the Polish weekly Przekrój published an advertisement for Dan-Mark exercise books, bearing the logo of 4fun.tv, a Polish music/interactive  TV station. Part of the advertisement contained a definition of the word "exercise book". The wording looked familiar, and Wikinews consulted Wikipedia,  the collaborative online encyclopedia. Upon seeing the Wikipedia definition, it appeared that the entry quoted in the promotional material was identical to the initial two paragraphs of the relevant Wikipedia entry.
Readers of online encyclopedias can edit the contents.