Owing to the ever-increasing number of publications it has become more and more difficult for scientists to find physics data relevant to their respective activities in the primary scientific and technical literature. With the exception of their special field of research they have to rely on data compilations. In many fields of physics, however, such data compilations do not exist or do not fulfill the requirements of the users, either because they are out of date or because they are published in places that are not well known. This unsatisfactory situation has been confirmed by an inquiry performed by the German Physical Society in 1972.