Most journals recommend that in referencing an electronic source one first make a printed copy of the document for one's own records. The text of the Guide will print out at about 30 pages. Beyond that please feel free to copy and paste the following citation. If you are writing *.html, feel free to copy the table code template for use with the "References Cited" section of your own electronic publication.
Stelle, Lenville J.
2001
An Archaeological Guide to Historic Artifacts of the Upper Sangamon Basin. Center For Social Research, Parkland College. http://virtual.parkland.edu/lstelle1/len/archguide/documents/arcguide.htm