Examples of citations for PNAS
Here are three examples of citations from Proceedings of the National Academy of Sciences, USA, a well respected scientific journal (often called just PNAS by scientists).
1. Neuhaus J-M, Sitcher L, Meins F, Jr, Boller T (1991) A short C-terminal sequence is necessary and sufficient for the targeting of chitinases to the plant vacuole. Proc Natl Acad Sci USA 88: 10362-10366.
2. Kellert S (1996) The Value of Life: Biological Diversity and Human Society (Island Press, Washington, DC), 2nd Ed, pp 13-34.
3. Hill AVS (1991) in Molecular Evolution of the Major Histocompatibility Complex, eds Klein J, Klein D (Springer, Heidelberg), pp 403-420.
Citation 1 is a journal article citation, 2 is a book citation, and 3 is a book chapter citation.