The rationale behind public book-burning, the suppression of free speech and ideas, swiftly evolved into a general tactic that was cast into an administrative framework. Joseph Goebbels' Ministry of Propaganda undertook the supervision of all aspects of cultural and intellectual life. In December of that year, more than 1,000 titles and the complete works of several authors were banned. By the end of the next year, more than 4,000 publications were so treated. Goebbels set up a dense network of 41 propaganda officers across the Reich. After the Nazis completed their takeover of radio broadcasts in the spring of 1933, the Nazis turned against the press. Orders and restrictions were placed on publishing houses, limiting freedom of the press to a small domain that the press could find between the lines. Intermittent acts of book-burning continued across Germany throughout the year.