Citing a numerical database in APA style

In a search today for a guide to citing a web-based numerical database (like CRSP or Compustat) in APA format, I ran across this great guide from the library at the University of North Carolina at Greensboro. As you can see, it gives examples for a number of databases we have here at Baruch. The following citation guides, which usually are pretty comprehensive and ones I tend to rely on, didn't have exactly what I was looking for:

• Online! by Harnack and Kleppinger
• Diana Hacker's guide
• APA's own guide on its website
• Duke University Libraries guide

Oddly, the MLA guide to citing electronic sources that is on the library website at the University of North Carolina at Greensboro isn't nearly as good as the APA one.