That the field of Mossbauer spectroscopy continues for the remarks section of the index, and the inclusion to be an important growth area in science and tech of some new appendices and tables (such as the en nology, despite recent economic pressures, is ade ergy conversion tables, nuclear radius and moment quately evidenced by the present volume. Covering re data, and the report of the ASTM Task Group on search published only in the year 1969, its size is com Mossbauer Nomenclature and Conventions). The parable to its predecessor, Mossbauer Effect Data advertisement section, too, provides a collection of Index 1958-1965. With such continuing growth in information useful to many readers. many fields, the need for specialized information re In summary, the new editors are to be congratulated trieval tools for the research worker is now becoming for their excellent and tremendous effort in putting together such a fine compilation in a remarkably short an increasingly important internationally recognized time. The user community, I am sure, will strongly concern. MEDI 1969 satisfies much of this need for the community it addresses in a timely manner. urge them to continue this series, as I know their pred This work not only follows in the footsteps of its ecessor has been urged to help fill the gap for the years 1966-1968. predecessor, but also includes a number of important and very useful innovations. Among these are the classification of substances investigated according to ARTHUR H. MUIR, JR.