The biography uses mostly 'secondary' sources. [=information that did not come from original/primary sources but came from research done by others]
There are some 'secondary' issues/considerations which must be taken into account as well.
In some children's books, the text is 'secondary to' the illustrations.
(..) I want to make a toast to Mason! Mason, I know not wanted a party tonight, but ... #we do. Just finish secondary once in life! And I want festejarte, and celebrate the next stage ... You will learn both the university. You'll laugh so much. Have teachers who inspire you. (..)2014 Boyhood
(..) - It seems quiet. - Yes, it is. - It also goes to the University of Texas? - Yes. What are you studying? History and Italian ... as a secondary subject. Want to teach? I dunno. I think he is still thinking. He already decided. He's smart. And where you live when you come here? I'm not sure. (..)2014 Boyhood