The standard Discover Magazine recipe that's delivered with Calibre no longer works. The output mobi file contains a bunch of "failed feed" messages. I believe the problem started when the site's RSS feeds moved to FeedBurner.
Fortunately I found that I'm able get most of what I want by creating a basic news recipe. The basic recipe was working fine until today when I noticed one news article was incomplete. When I checked the website I saw the following: "This article is only available to registered users of DISCOVERMagazine.com. Register now for FREE and get instant access!"
The FeedBurner page is:
http://feeds.feedburner.com/20ThingsYouDidntKnowAbout
The story on the page is called: 20 Things You Didn't Know About... Hibernation
The direct link to the story is:
http://discovermagazine.com/2013/mar...r#.URgbcWdgWMc