In the first two Parts of Volume 3/38 Optical Constants critically evaluated data on refractive indices of inorganic and organic liquids and their wavelength dependence (dispension) are provided. Part A contains the inorganic, organometallic, and organononmetallic liquids, and the binary liquid mixtures (about 900 pure substances and their mixtures). Part B contains data of more than 7600 organic liquids. Since not all data for the organic compounds and mixtures could be included in the printed version the second part additionally contains an electronic version of the complete collection with all available data and references.