Bertrand Russell buch Sceptical Essays
Gedankenfreiheit und offizielle Propaganda. In: „Wissen und Wahn: skeptische Essays“, Drei Masken Verlag, Berlin 1930 <br class="br">("It is clear that thought is not free if the profession of certain opinions makes it impossible to earn a living. It is clear also that thought is not free if all the arguments on one side of a controversy are perpetually presented as attractively as possible, while the arguments on the other side can only be discovered by diligent search.") Sceptical Essays, Ch. 12: Free Thought and Official Propaganda, books.google https://books.google.com/books?id=9tQsg5ITfHsC&pg=PA127&dq="diligent+search", archive.org https://archive.org/stream/freethoughtoffic00russuoft/freethoughtoffic00russuoft_djvu.txt
