If you only LEARN JUST ONE THING from all of these pages, let it be this topic. You, and all other researchers who ever look at your materials, will thank you. The reasons:
One of the most important parts of any genealogy written for others to see is a complete citation of the source for every piece of genealogical information (aka. source document extraction)
A full citation should allow anyone to go easily to the exact place where the author found the information
A full citation should include the title and edition number, author, publisher, place and year published, volume and page number, and, any other pertinent information
Most genealogical books either leave these out altogether or show very few of them, often not complete. Genealogical data CDís and web sites with family information rarely give any clue as to where the data came from.
Examples of complete citations:
Birth certificate for John Q. Smith, May 13, 1903, Cambria County Pennsylvania court house, Altoona, vol. II, page 47, number 18
Doe, Jane, The Harris Family History, (1965, Cleveland, ABC Publishers), page 14
1860 U.S. Census, Jackson county, Missouri, Kaw township, p. 187, line 22, National Archives Microfilm M-019, roll 51
1826 tax list (real and personal property), Baldwin county, Georgia, 4th District, page 2, line 4, Microfilm collection, Georgia Department of Archives and History, Atlanta
Family Bible Record of Paul Clark of Charleston, West Virginia, The Holy Bible, Containing the Old and New Testaments, Revised, (1852, New York, D.B. Crown), owner in 1972 was Betty Richardson, 112 S. Main Street, Topeka, KS 66511. Original record was handwritten, probably by Martha, the wife of Paul Clark. All writing is clear and legible.
Union Service record for Captain Joshua C. Fillmont, muster roll, July 1863, Co. B 32nd regiment, Ohio Volunteers, Service in the Army of the United States of America, box 22, Ohio State Archives, Columbus
Deed of sale from Jacob Miller to Henry Bowden, January 26, 1771 (recorded February 2, 1771), Montgomery county North Carolina. Deed book 15, pp. 10-11, North Carolina State Library, County Core Collection Microfilm No. 84-21.
Headstone inscription for George North, Antioch Cemetery, Warren county, Wisconsin (Sampson Lot, row 14, plot 41), visited by author June 18, 1988.
Oral interview with Margaret Rolands, October 15, 1993, by Oliver Phillips, recording owned by author, Pierre, South Dakota. Margaret was living in Omaha, Nebraska at the time of the interview and was 84 years old.
Obituary of Douglas P. Earhart, Clarion Ledger (LeMars, Plymouth county, Iowa), November 12, 1914, page 4, column 3, Iowa Archives and Natural History, microfilm number 16, Des Moines, Iowa.
See the book Cite Your Sources by Richard S. Lackey (1980, Jackson, MS, University Press of Mississippi, Jackson, MS, $15) for more specifics on how to write correct citations.