 Censorship at first targeted books that were considered to be " serious " , including scientific and educational texts and texts that were thought to promote Polish patriotism ; only fiction that was free of anti @-@ German overtones was permitted . Banned literature included maps , atlases and English- and French @-@ language publications , including dictionaries . Several non @-@ public indexes of prohibited books were created , and over 1 @,@ 500 Polish writers were declared " dangerous to the German state and culture " . The index of banned authors included such Polish authors as Adam Mickiewicz , Juliusz Słowacki , Stanisław Wyspiański , Bolesław Prus , Stefan Żeromski , Józef Ignacy Kraszewski , Władysław Reymont , Stanisław Wyspiański , Julian Tuwim , Kornel Makuszyński , Leopold Staff , Eliza Orzeszkowa and Maria Konopnicka . Mere possession of such books was illegal and punishable by imprisonment . Door @-@ to @-@ door sale of books was banned , and bookstores — which required a license to operate — were either emptied out or closed . 
 Censorship at first targeted books <a href='null_relcl' title='1'><mark>that</mark></a><a href='uninflect' title='2'><mark>were</mark></a> considered to be " serious " , including scientific and educational texts and texts <a href='null_relcl' title='3'><mark>that</mark></a><a href='uninflect' title='4'><mark>were</mark></a> thought to promote Polish patriotism ; only fiction <a href='null_relcl' title='5'><mark>that</mark></a>was free of anti @-@ German overtones was permitted . Banned literature included maps , atlases and English- and French @-@ language publications , including dictionaries . Several non @-@ public indexes of prohibited books <a href='uninflect' title='6'><mark>were</mark></a> created , and over 1 @,@ 500 Polish writers <a href='uninflect' title='7'><mark>were</mark></a> declared " dangerous to the German state and culture " . The index of banned authors included such Polish authors as Adam Mickiewicz , Juliusz Słowacki , Stanisław Wyspiański , Bolesław Prus , Stefan Żeromski , Józef Ignacy Kraszewski , Władysław Reymont , Stanisław Wyspiański , Julian Tuwim , Kornel Makuszyński , Leopold Staff , Eliza Orzeszkowa and Maria Konopnicka . Mere possession of such books was illegal and punishable by imprisonment . Door @-@ to @-@ door sale of books was banned , and bookstores — which required a license to operate — <a href='uninflect' title='8'><mark>were</mark></a> either emptied out or closed . 
Censorship at first targeted books was considered to be " serious " , including scientific and educational texts and txts was thought to promote Polish patriotism ; only fiction was free of anti @-@ German overtones was permitted . Banned literature included maps , atlases and English- and French @-@ language publications , including dictionaries . Several non @-@ public indexes of prohibited books was created , and ova 1 @,@ 500 Polish writers was declared " dangerous to da German state and culture " . Tdaindex of banned authors included such Polish authors as Adam Mickiewicz , Juliusz Słowacki , Stanisław Wyspiański , Bolesław Prus , Stefan Żeromski , Józef Ignacy Kraszewski , Władysław Reymont , Stanisław Wyspiański , cj Tuwim , Kornel Makuszyński , Leopold Staff , Eliza Orzeszkowa and Maria Konopnicka . Mere possession of such books was illegal and punishable by imprisonment . Door @-@ to @-@ door sale of books was banned , and bookstores — which required a license to operate — was either emptied outt or closed .