Seven bibliographies/bibliographic databases have been analysed as regards their subject area, list of scanned periodicals, article coverage and overlap. These bibliographies are: A. Computer and information systems abstracts. B. Computer abstracts. C. ICP software directory. D. Computing reviews. E. Computer and control abstracts. F. Computer program abstracts. G. Bulletin signaletique, section 110. Only five bibliographies cover the whole of the subject area examined. A great difference exists between the number of periodicals scanned (73 to 2771) and between the percentage of articles included from six carefully selected periodicals (27% in D to 83% in G). This results in a small overlap between the examined bibliographies. Bibliography B selects most precisely, and in spite of the low number of periodicals scanned, B includes the highest number of unique references. E and G are the largest bibliographies, containing the whole subject area, and moreover they are the only ones searchable online. These are therefore compared with two other databases that contain at least a part of the examined subject area: H. Mathematical reviews. J. Zentralblatt für die Mathematik. The article coverage of H and J (resp. 41% and 48%) remains far below the article coverage of E and G (resp. 74% and 85%). From a small examination of the allocated indexing terms it appears that not one article has been assigned similar index words in the various bibliographies. Hence, for a reliable literature study the bibliographies/databases A, B, E, G, H and J all have to be searched, whilst the search profile has to be adapted for each bibliography.