1a. Jordan R. Dodd, ed.  1993.  Virginia Marriages:  Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-229):

Long, Gabriel

Slaughter, Lucinda

14 Oct 1805

Culpeper Co.

1b.  Raleigh Travers Green.  1958.  Genealogical and Historical Notes on Culpeper County, Virginia: Embracing a Revised and Enlarged Edition of Dr. Philip Slaughter's History of St. Mark's Parish.  Southern Book Co., Baltimore, MD (online at GenealogyLibrary.com):

p. 45	Following the notes from wills we give the complete marriage record of Culpeper from the year 1781 to January 1, 1825.
p. 55	MARRIAGE RECORD. [Note: The year of marriage only is given. From 1781 to 1825.]
p. 65	Gabriel Long, Lucinda Slaughter, '05.

2.  Census Index:  U.S. Selected Counties, 1810 (Broderbund CD-313):

1810

Long, Gabriel

VA

Culpeper Co.

p. 101

00102-101010-40

3.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  District No. 1, Christian Co., KY, p. 488, 815/876, enumerated 5 Oct 1850 (extracted by Diana Gale Matthiesen — this record very difficult to read).

Lucy Long	65	F		Va
Thos W Long	24	M	Farmer	Ky
Eliza ? Long	20	F		Ky

Thomas LONG is probably Lucy's grandson, and Eliza is his wife (newly wed in 1849).

4.  Messages in the Long Family Genealogy Forum (online at GenForum).

5.  LDS.  Family Search: Internet Genealogy Service: IGI - International Genealogical Index and AF - Ancestral File (online at FamilySearch.org).

6.  FamilyTreeMaker User Home Page.