The Mossbauer effect is not only one of the simplest and most beautiful discoveries of nuclear phYSics, it is one of those discoveries which, to the highest degre'e, tend to produce and develop new ties between nu­ clear physics and the other branches of physics as well as the other natural sciences and engineering. Two of our earlier papers which form the basis of this monograph were devoted to "propaganda" for the Mossbauer effect among chemists and "propaganda" for the chemical applications of the effect among nuclear physicists. The first paper, presented in January 1962 at the Scientific Colloquium of the Learned Council of the Theory of Chemical Structure, Kinetics, and Reactivity of the Di vision of Chemical Sciences of the Academy of Sci­ ences of the USSR, gave a general description of the Mossbauer effect and the methods by which it is observed" and enumerated a number of problems in structural chemistry, chemical kinetics, and radiation chemlstry that might well be studied by observing the Mossbauer spectra, in particular those of organotin compounds.