4. Other acquisition sources
If the coverage of a subject or programme is to be comprehensive, then it is often necessary to exploit sources other than the recording activities of one's own institution in order to acquire appropriate acoustic material. In this respect one should consider co-operating with outside researchers who have similar research interests and who, in return for help with practical aspects and equipment, will supply material to the archive. It would make good sense for those institutions which are responsible for preserving the cultural heritage of particular regions or countries to follow such a policy and to do their utmost to collect historical material as well. For this reason they should make contact with other institutions and private collectors, as well as with radio stations, record producers and foreign sound archives. Newly established sound archives in Third World countries have already begun to enhance the historical content of their national collections by systematically collecting previously recorded material from these other sources.