1.  Marriage Record: 

2.  State of Minnesota.  c2002.  Minnesota Birth Index, 1935-2002.  Minnesota Dept. of Health, Minneapolis, MN (online at Ancestry.com):-

Name:	Annette Magdalen Westergard	Olga Alvina Westergard	Alma Karen Westergard	Arvin Dennis Westegard	Arthur Benth Anton Westergard
Birth Date:	9 Oct 1936	7 Nov 1938	15 Jan 1941	18 Jan 1944	14 Jul 1945
Birth County:	Otter Tail	Otter Tail	Otter Tail	Otter Tail	Otter Tail
Birth State:	Minnesota	Minnesota	Minnesota	Minnesota	Minnesota
Father:	Anton Westergard	Anton Westergard	Anton Westergard	Anton Westegard	Anton J Westergard
Mother:	Olga Carter	Olga Carter	Aloja Florence Carter	Olga Carter	Olga Florence Carter
File Number:	1936-MN-024268	1938-MN-013559	1941-MN-024482	1944-MN-054653	1945-MN-013693

3.  1920 Census Every-Name-Index/Images (online at Ancestry.com, Image #6 of 13 — indexed "Anton Westergard"):  Trondjem Twp., Otter Tail Co., MN, Roll T625_849, p. 261B, SN 3B, SD 9, ED 166, enumerated 14 Jan 1920, official enumeration date 1 Jan 1920 (extracted by Diana Gale Matthiesen):

1920:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
2	3	4	5	6	9	10	11	12	13	14	15	17	18	19, 21, 23	20, 22, 24	25	26	27	28	29
Fm	49	49	Westergaard Anton	Boarder	M	W	35	S	1911	Na	1917	Y	Y	Denmark	Danish	Y	Farmer	grain farm	OA	41

Boarding w/SORENSON family.

4.  1930 Census Every-Name-Index/Images (online at Ancestry.com, Image #6 of 13):  Maplewood Twp., Otter Tail Co., MN, Roll 1111, p. 83B, SN 3B, ED 56-53, SD 4, enumerated 11 Apr 1930, official enumeration date 1 Apr 1930 (extracted by Diana Gale Matthiesen):

1930:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
3	4	5	6	7	10	11	12	13	14	16	17	18	19	20	21	22	23	24	25	26	27	28	30	32
63	65	Westergaard Anton	Head	O	Y	M	W	46	S	N	Y	DK	DK	DK	Danish	1911	Na	Y	Farmer	General Farm	O	Y	N	56
		Dahl Nels	Lodger			M	W	22	S	N	Y	MN	MN	MN				Y	Laborer	Farm	W	Y	N

Listed 12 households from future wife, Olga (CARTER) CLINE, and her first husband.

5.  State of Minnesota.  c2002.  Minnesota Birth Index, 1935-2002.  Minnesota Dept. of Health, Minneapolis, MN (online at Ancestry.com):

Name:	Anton J Westergard	Olga F Westergard
Birth Date:	5 Feb 1884	13 Aug 1906
Death Date:	23 Oct 1975	24 May 1987
Death County:	Clay	Clay
Mother's Maiden Name:		Rickenberg
State File Number:	024849	011602
Certificate Number:	024849	011602
Certficate Year:	1975	1987
Record Number:	2643227	2251623

6.  SSDI:  Social Security Death Index (online at RootsWeb.com):

Name	Birth	Death	Last Residence	SSN	Issued	Post-em
Anton WESTERGARD	05 Feb 1884	Oct 1975	56534 (Erhard, Otter Tail, MN)	470-40-4435	MN	Yes
Olga WESTERGARD	13 Aug 1906	May 1987	56514 (Barnesville, Clay, MN)	472-76-4008	MN	Yes

7.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).

8.  Messages posted to the Westergard Family Genealogy Forum (online at GenForum.com).

9.  Email from descendant.