Ask HN: Proper source attribution in covering news?

We are getting ready to release a new site related to our vertical-market of interest. One thing we'd like to have on our site is a news section where we can cover breaking news that we feel is relavent to our readers. Are there proper guidelines for sourcing where you find the news you are covering. For example, if I find out about a news article via another news site, can I go to the source and bypass giving credit to the place where I found the post? I've noticed on engadget that they provide two source links. One call "via" that covers the blog that posted on the topic and one called "source" that goes to the core article or press release. I'm wondering why engadget would give attribute to the "via" and not just post the source. Maybe these were tips sent to them and they decide to give credit to the blogs that gave them the tip. Any guides on this topic is appreciated.