1a.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):

Holt, John

Walker, Mary

3 Mar 1831

Coshocton Co.

1b.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

John HOLT Spouse: Mary WALKER Marriage: 03 Mar 1831, Coshocton, Ohio Source: Marriage Records, 1811-1917. Ohio. Probate Court (Coshocton County)

1c.  Jordan R. Dodd, ed.  1998.  Marriage Index: Ohio, 1851-1900.  Liahona Research, Orem, UT (Broderbund CD-236):

Holt, Isaac	Smith, Elmire	20 May 1865	Coshocton Co.
Sheldon, George W.	Holt, Sarah	12 Oct 1871	Coshocton Co.
Farquhar, V. B.	Holt, Elizabeth	17 Dec 1872	Coshocton Co.

2.  1840 Census Index/Images (online at Ancestry.com, Image #3 of 8; extracted by Diana Gale Matthiesen):

1840

OH

Coshocton Co.

Tiverton Twp.

Roll M704_387

pp. 359B-360A

Ln. 30

John Holt

221 001 - 101 010

0200000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
2 males	4 or under	1835-1840	= Son A = Moses (b. 1836)
2 males	5-9	1830-1835	= Abraham (b. 1835) = Joseph (b. 1833)
1 male	10-14	1825-1830	= ?
1 male	30-39	1800-1810	= John (b. 1808)
1 female	4 or under	1835-1840	= Rebecca (b. 1838)
1 female	10-14	1825-1830	= ?
1 female	20-29	1810-1820	= Mary (b. 1811)
2	persons employed in agriculture

The teenagers were born before John & Mary married.  Did John have a prior marriage?  Listed next to Mary's father, Joseph WALKER (æ 50-60) and five lines from John's brother, Stephen.  The only HOLT/HOLDTs in the county are our subject, his brother, Stephen, and his father, John Sr.

3.  1850 Census Every-Name-Index/Images (online at Genealogy.com; Image #12 of 21 — image is missing at Ancestry.com and difficult to read at Genealogy.com):  District 27, Tiverton Twp., Coshocton Co., OH, Roll M432_670, p. 49B, 88/88, enumerated 15 Aug 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

John ? Holt	41	M		Farmer	600	Pa
Mary      "	38	F				Ohio
Joseph    "	16	M		Laborer		"
Abraham   "	15	M				"
Moses     "	13	M				"
Rebecca   "	12	F				"
John      "	10	M				"
Isaac     "	6	M				"
Elizabeth "	2	F				"
Sarah     "	4/12	F				"
Amanda Johnson	14	F				"
Soloman Conner	16	M		Cooper		"
Joseph Walker	68	M			260	Pa
Mahala   "	36	F				Ohio	Idiot

Joseph WALKER is almost certainly Mary's father, and Mahala is probably her sister.

4.  1860 Census Index/Images (online at Ancestry.com, Image #22 of 23):  Yankee Ridge P.O., Tiverton Twp., Coshocton Co., OH, Roll M653_950, p. 218B, PN 22, 152/154, enumerated 20 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Mary Holt	48	F		Farmer	1200	358	O
Moses   "	23	M		Farm labor			"
Rebeca  "	22	F					"
John    "	20	M		"    "			"
Isaac    "	16	M		"    "			"
Elisabeth "	12	F					"
Sarah     "	10	F					"
Joseph Waker	78	M		Retired farmer	3500		Penn
Solomon Holt	21	M		day laborer			Ohio

Solomon HOLT is Mary's nephew, son of her late brother, Stephen HOLT.

5.  Participant in the HOLT Y-chromosome DNA Surname Project at FamilyTreeDNA.