A side note, how do you go through a reference and lift all the information from it while avoiding simply paraphrasing it? Or are you using it as a starting point then finding more sources on these mayors?
With copyrighted encyclopedias, my preference is to use at least 2-3 sources for a bio. For example, with a physicist, I'd use a biographical dictionary / encyclopedia as a reference for basic biographical facts (dates, locations, awards, etc.), and then flesh out information about scientific importance from something like a textbook or survey paper commenting on his/her work.
If the main source is a non-encyclopedia, it's usually less of a problem, because the original text doesn't really read like an encyclopedia article anyway. For example, when writing articles on Greek archaeological sites, my source material is usually a discussion in a monograph or history book, which is sometimes scattered (it may be mentioned for a few pages in Chapter 2, then again in Ch. 8, sometimes as a main topic, other times in passing when discussing an event or person, that kind of thing). So it's a matter of going through, noting down salient facts and page numbers they came from, and then assembling the results into an article.