External Links (How many?)

Its really hard to say with out being able to see the site, its structure, its content and how its presented. There is no golden rule of how many links is good or bad but the fact your asking this question says to me that you believe there could be too many for the amount of content on that particular page, if your thinking that then what are visitors going to think ? Does that page offer visitors any value or is it just a page with a bit of text linking to the money site ?.

Think of it how your visitor will see it, 2 of 3 quality references will always be better than 10 - 20 half arsed references which are most likely liked to bloat/thin content category pages anyway.

Like i say though its hard to give a non-generic answer with out seeing what your talking about.