You need to keep track of the information sources you find as you search. It's best to store the complete bibliographic details for each resource in one place as you go, thus eliminating the need to repeat searches unnecessarily.
Methods for saving citations include using:
An Excel workbook with:
Saved search history
Note: EndNote takes time to learn. If you are doing a literature review as an assignment or project for your coursework, Zotero might be easier to use. If you are a researcher or research higher degree student, it's worth taking time to learn to use EndNote because you will be managing large numbers of references.
A literature matrix will help you pull all of your references and notes together ready for synthesis into your review. It's basically a table with all of your references, noting whether or not each will be included in the review and why, and your notes from the critical reading. You can use a spread-sheet or Word document for this.
Your column headings will depend on the type of review you are doing and your focus. You are using them to categorise your findings. Examples include:
Note: If your review is designed to answer a multipart question, you could record the subtopic each resource is associated with in a column of a combined matrix. Alternatively, you could have a different matrix for each subtopic.
Here's an example from Griffith University: Creating my own database (video) (about 15 minutes).