These are commercial databases, databanks, encyclopedias, dictionaries, etc. containing materials useful to classicists and offering immediate on-line lookup. Use of the term "commercial" does not imply "private" or "for profit." Many commercial sites also have free materials of interest (some quite scholarly and valuable), so be sure to explore their pages. Potential subscribers are cautioned to use the test subscriptions first. Sometimes the paper version has more complete articles than the online version; the reverse is also possible.