Since publication of the previous (fourth) edition of this handbook by UNESCO in 1978, drastic technological progress and very important changes in the political-economic sphere have taken place, with great impact on library work. The international exchange of publications continues to be an important mode of collection building and is practiced by almost all major libraries. The 5th edition of the Handbook addresses these changes in all three parts: Practices (sources of documents, organization and methods), History and Current Examples (e.g. international book exchange: has it any future in the electronic age?) and the Directory (list of exchange centres, selected bibliography).