A literature review involves both the literature searching and the writing. The purpose of the literature search is to:
List above from Conducting A Literature Search, Information Research Methods and Systems, Penn State University Libraries
A literature review provides an evaluative review and documentation of what has been published by scholars and researchers on a given topic. In reviewing the published literature, the aim is to explain what ideas and knowledge have been gained and shared to date (i.e., hypotheses tested, scientific methods used, results and conclusions), the weakness and strengths of these previous works, and to identify remaining research questions: A literature review provides the context for your research, making clear why your topic deserves further investigation.
*Boolean logic provides three ways search terms/phrases can be combined, using the following three operators: AND, OR, and NOT.
The type of information you want to find and the practices of your discipline(s) drive the types of sources you seek and where you search.
For most research you will use multiple source types. Depending on your discipline(s), sources of interest may include: annotated bibliographies; articles from journals, magazines, and newspapers; books; blogs; conference papers; data sets; dissertations; organization, company, or government reports; reference materials; systematic reviews; archival materials; curriculum materials; and more. It can be helpful to develop a comprehensive approach to the types of sources you need and where you will search for each kind. Below are some steps you might include in your approach.
Utilize Current Awareness Services Identify and browse current issues of the most relevant journals for your topic; Setup email alerts, e.g., Journal Table of Contents, Saved Searches
Consult Experts Identify and search for the publications of or contact counselors, educators, scholars, librarians, employees etc. at relevant organizations, agencies, and practices
Remember there is no one portal for all information!