Duplicates and Facets
Almost 2300 sites are listed in 5 lists: ChemInfo, ChemDex, Yahoo, Netfirst and INFOMINE.
- 12 were common to 5 sites
- over 20 more were common to 4 sites
- every list had some unique sites
- up to 1/4 of the sites listed were duplicated in the same directory or subsets