From cards to clumps: a look at developments in the world of union catalogues

With shrinking local library resources and the growth of resource sharing, union catalogues, in one form or another, are an important feature in today's library world. This article takes a look at some of the developments in union catalogue production, from card catalogue to virtual union catalogues or clumps, and discusses their use for document access and supply. The IFLA World Directory of National Union Catalogues, a kind of union catalogue of union catalogues, is also described.