Answer:
periodical/trade journal
Explanation:
"Periodical/trade journals" refer to scholarly articles, which means that they are written by certain experts in particular industries. This also means that they are professional publications and may also include newspapers, journals, etc.
In order for Jennifer to know more of the person's work, she has to use the periodic/trade journal. This means that the sources that she will be referring to are similarly professional journals because the writer is an expert.
So, this explains the answer.