References

Pay attention to how the authors use references as you review the rest of the manuscript.

Some issues to watch for include:

Are there places where the authors need to cite a reference, but haven’t? (In general, citations are needed for all facts except those that are well-established, common knowledge; that come from the current study; or that are clearly phrased as the authors’ own hypothesis.)
Do the authors cite all the most relevant previous studies and explain how they relate to the current results? If not, note which references are missing.
Are the cited studies recent enough to represent current knowledge on the topic?
Do the authors cite the work of a variety of research groups? This is preferable to mainly citing papers from one or two research groups, especially if one of the most cited groups is one the authors belong to (although it is not always possible in very small fields of study).
Do the authors cite many review articles? It is better to cite the original studies.
Are all of the citations helpful to the reader? Note any places where the authors seem to be reviewing literature simply to show the depth of their knowledge, or to increase citations of their own previous work.
Do the authors cite findings that contradict their own (where they exist), as well as those that support their claims? It is important that the authors provide a well balanced view of previously published work.