He is married to Grietje de Vries.
Permission for the marriage has been obtained in Schoterland on July 1, 1906.Source 2
They got married on July 12, 1906 at Schoonebeek , he was 22 years old.Source 2Child(ren):
Geboorteregister 1883, Schoterland, Aktenummer A209
Huwelijksregister 1906, Schoterland, Aktenummer 82
Overlijdensregister 1920, Schoterland, Aktenummer A181
Overlijdensregister 1929, Schoterland, Aktenummer A193
http://www.graftombe.nl/names/info/385827/jonker