The New York Times article by Matt Flegenhiemer and Isold Raftery on the tragedy of the Powell family in Graham attributes its information to three different sources: Graham Deputy Fire Chief Gary Franz, Powell's lawyer Jeffrey Bassett, and the Associated Press, who spoke to Bassett and reported on the explosion first.
In the lead the article simply cites the "authorities" as a source, but goes on to specifically name Franz and quote him directly. The article also names Bassett, and clairifies that the information used is from Associated Press, who originally interviewed Bassett.
Franz is paraphrased more than he is directly quoted, and the article is better for it. The only complete sentence attributed fully to Franz is "these are the kinds of things that suggest very clearly this was an intentional act." This is an instance where Franz's credibility is valuble, and allows the Times to point to the conclusions being drawn about the explosion without making any statement about intention themselves.
The attributions are fairly easy to follow. It's especially helpful that when Bassett is attributed to additional information at the end of the article Flegenhiemer and Raftery clairify him as "the lawyer". This makes the information easy to follow with out having to look back up through the article for a name.
The article also always uses the word "said" in attributions. This is helpful because the word is able to "disappear" into the article and the information isn't weighed down by constant qualifiers and flowery language.
[I apologize for this late posting -- internet connection troubles.]