Here is what I found so far.
Anna Jungerman. I found a website showing the location of her grave with the following information:
Terpstra, Anna A. (Jungerman) b. Oct 3, 1910, d. Apr 8, 2001, s/w Hendrick Terpstra, Center Section
(Hendrik is also buried there)http://www.interment.net/data/us/wi/sauk/pleasant/valley.htm
Assuming the birth year is correct, I found only one birth record matching the year on wiewaswie.nl
DOB:maandag 28 september 1896
Date:maandag 28 september 1896
Place:Smallingerland (located in the province of Friesland)https://www.wiewaswie.nl/personen-zoeken/zoeken/document/a2a...
One issue is that his immigration record on Ancestry.com lists Hendrik Terpstra arriving in New York from Rotterdam on 24 FEB 1916 on the ship "Nieuw Amsterdam"
His birth date is listed as "ABT 1897"
His age is listed as 19
His birthplace is listed as "drachtein" which is a town/place located in Smallingerland
I would assume they wrote down the wrong birthdate? since the location and name matches the birth record.
Looking at the scan of the document, the handwriting is hard to read but it appears his listed occupation was a carpenter. Also, can't tell if he he came by himself for sure (I can't read the heandwriting in the document) but it does look like it.
Also on Ancestry is records on:
1930 census which shows him married to Anna and living in Excelsior, Sauk, Wisconsin.
His naturalisation papers showing it took effect on 2 NOV 1918 in the court district of Illinois, Indiana, Wisconsin, Iowa. (This document lists his correct birthdate unlike the immigration records).
Also his WW1 draft registration card listing him in the La Crosse County, Wisconsin.
All of these records would back the birth certificate found on wiewaswie.nl as being your Hendrik Tepstra.
A quick look on google found the following link to a family tree which if correct, list further ancestors for Hendrik Tepstra.http://www.genealogieonline.nl/stamboom-deelstra-bijker/I214...