Abstract: The invention relates to a procedure for searching for data through a number of databases, each of which contains a large number of data items of a first given type, each associated with at least one data item belonging to a second data type. For a reference data item, the procedure covers the search for data of the second type associated with the reference data item, the number of data items of the first type associated with each data item of the second type, and then the allocation of a coefficient known as the “relevance weighting” (a function of the number of data items of the first type associated with the particular item of the second type) to each set of data of the first type associated with the data item of the second type.