Cataloguing computerization is at present widely engaged in French university libraries. It is performed according to the principle of network cataloguing within one of the three sources approved by the Central administration : Sibil-France, OCLC and BN Opale. How did libraries choose their system, what is the importance of each of the three groups, their productive capacity in relation to their acquisitions ? Such are the questions approached at first, before coming secondly to a comparative cost of the entry according to the chosen source. A study carried out in 1992 on a sample of 43 university libraries, tends to prove that this cost is less depending on the source itself than on the organization of work and staff put into effect.