Department of Geosciences
North Dakota State University
Have a look at a recent issue of Geology or the Bulletin of the Geologic Society of America (GSA) for more examples.
Fischer, T.P., Arehart, G.B., Sturchio, N.C. and Williams, S.N., 1996, The relationship between fumarole gas composition and eruptive activity at Galeras Volcano, Colombia: Geology, v. 24, p. 531-534.
If you wish to cite a web page, give the author's name (if known), the full title of the work, the title of the complete work if applicable, the date of access, and the full http address.
U.S.G.S., 2006, New Information on the Long-Term Fate of Ammonium in Ground Water, http://toxics.usgs.gov/highlights/nh4_gw/ , accessed 9 Aug. 2012.
There are recommendations for citation of electronic information given at http://www.wpunj.edu/library/citing-electronic-resources.dot.