Sources in Selfkant / Jülich

[mk1992]

Hi everyone,

Although I have made more and more progress with other family links, my own descendancy has been stuck for a long time.
My family originated from Schalbruch in Germany, part of the parish of Havert (Selfkant) where the church archives seem the only registration of the population.

I have not been able to find any sources pre-1750, not from the town, or the region or anything.
Pre-1750 the area should have been part of Herzogtum Jülich, with the region belonging to Canton Sittard.
Can somebody point me to sources from that area/time?