Scholarship is the product of scholars. Scholars are students who have devoted much time and energy to a particular subject. In order to be considered a scholar, one must publish his work (make public). In the free market place of ideas, the scholar's work is critically evaluated and measured against the existing literature on the subject. In most cases, scholarship is a secondary source. One major exception to this is the study of historical interpretations or historiography. In that case, the history itself is the primary source.
As you build your bibliography, pay attention to the titles that you see frequently. To stay current in your career, you will want to read one or two professional journals. Now is the time to identify them and to see which ones will serve you best.