Review materials are a good way to familiarize yourself with trends and key ideas in a field of study. These are usually annual or monthly cumulations of articles or citations to articles that give you a brief summary of research and findings on a particular topic.
Encyclopedias and bibliographies review the state of research in an area or on a topic and refer you to additional sources. Encyclopedia entries often have a list of works cited at the end that point you to relevant readings while bibliographies list foundational citations on a given topic.