The document outlines skills and methods for analyzing sources from the 1920s. It defines primary and secondary sources, and explains that primary sources were created during the event while secondary sources discuss past events. It also discusses how to identify credible and reliable sources by looking at citations, references, consistency, and reputation. Additionally, it explains how historical circumstances can impact an author's perspective and purpose. Finally, it distinguishes between bias, which involves strong opinions not always backed by evidence, and facts, which can be proven with evidence to support statements of truth.