Presents experimental and theoretical papers on the spectroscopy of excitons bound to isoelectronic impurities of the iron group transition metals. Particular attention is paid to the study of bound excitons by means of optical modulation methods especially the electroabsorption method. Other titles in this series include "Non-Centrosymmetric Langmuir-Blodgett Films", "X-Ray Diffraction of Nematic, Smectic A and C Liquid Crystals", "The Dynamics of Planetary Rings and the Prediction of New Uranian Satellites", and "Theory of Photothermal and Photoacoustic Diagnostics of Semiconductor Structures".