Mach2 - 4:41 pm on Aug 4, 2010 (gmt 0)
Furthermore, I would argue that it's perfectly "natural" to ask someone who re-uses, quotes or references your content to link directly to that content as a citation. That's not an unnatural link, it's a genuine endorsement.
Indeed, in many cases it seems like you pretty much have to have external links with relevant anchor text for deep pages to rank for hard terms.
If you're getting those links by convincing people who reuse your content to link to you, I seriously doubt you're going to get flagged as spam.
I agree and this is a parctice I particulary use and recommend.