1. A method of constructing a network of conceptual entities and their relationships, in which data processing means is used to scan at least one database of text documents referring to concepts so as to identify concepts by scanning for concept abbreviations, to note co-occurrences of concepts in the same article, to record information representing the co-occurrences and the number of documents in which they appear, and to provide a network representing relationships between concepts, wherein concepts are also identified in documents by means of scanning for concept names and in that at least some abbreviations are only accepted as representing a reference to a concept in a document if the scan reveals that at least one word from one name of the concept also appears in a suitable part of the document.