One of two major functions of libraries, technical services include processes for acquiring, arranging, indexing, and storing the collection. The output of published materials, in all forms, is so vast that no single library, not even the largest, can hope to acquire everything; even in relatively specialized fields, some selection has become necessary, and most libraries have an explicit selection policy. The basic principles of selection vary little among different types of libraries, inasmuch as they derive directly from the known interests of the users. Practice is another matter and varies according to the types of user. A national library ...(100 of 18999 words)