He is married to Jimkje de Graaf.
They got married on May 25, 1918 at Kollumerland c.a., Friesland, Nederland, he was 23 years old.Source 3
grandparents
parents
brothers/sisters
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Jetze Koster | ||||||||||||||||||
1918 | ||||||||||||||||||
Jimkje de Graaf | ||||||||||||||||||
Geboorteregister 1894, Kollumerland c.a.
https://www.graftombe.nl/names/info/537256/koster
Huwelijksregister 1918, Kollumerland c.a.