Secrets of Spreading Rumors
3. Particular rumours should be designed to appeal to particular groups (i.e., Catholics, or ethnic groups such as Czechs, Poles, etc.)
4. A particular rumour should have a specific purpose.
5. Rumours are most effective if they can be originated in several different places simultaneously and in such a way that they shuttle back and forth, with each new report apparently confirming previous ones.
Advice as valid today as it was in the 1940s.