"Army Map Service receives many requests for information about how we catalog, file, and circulate maps. The map differs so much from standard library material, it requires storage techniques, records, and reference techniques quite different from the rest of the library collection. This paper is an attempt to describe a system which would be applicable to the average depository map library. We have reviewed our own system and selected those elements we consider essential to any good reference file. We have tried to bring these elements together to form a system that would be easy to apply and economical to use."--Introduction.