[Tango-artists] Terms Of Use: Who is "the author"?

[Linimair Simon]

Dear Tango-Artists,

In the first mail I sent, I forgot to specify a subject, so I decided
to post my message again:

I would like to use your wonderful icons in a commercial closed-source 
application. According to the licence-text 
(http://creativecommons.org/licenses/by-sa/2.5/), I will have to
"attribute the work in the manner specified by the author or licensor", 
but I'm not sure who actually is the author or the licensor.

In fact I'm looking for a FAQ-Entry like 
"How can I use the Tango-Icon-Set in my application?"

Thanks in advance for your answers.

Simon