The Evidence Based Medicine Guide provides an overview of EBM with information on levels of evidence hierarchies and UK Library resources by evidence level.
An important step in writing a paper is showing the strength and rationale of the evidence you chosen. The following document discusses the reasoning, grading, and creation of a "Table of Evidence." While tables of evidence can differ, the examples given in this article are a great starting point.
The ebook, Literature Reviews for Nursing and Education Graduate Students: Chapter 7 Synthesizing Source has examples of creating a literature matrix.