Rapid methods for measuring radioactivity in the environment proceedings of the international symposium on rapid methods for measurement of radioactivity in the environment organized by the government of the Federal Republic of Germany in co-operation with the Gesellschaft für Strahlen- und Umweltforschung mbH München, with the co-sponsorship of the International Atomic Energy Agency, and held in Neuherberg bei München, 5-9 July 1971