Atze Sijtsma was a respected Dutch violin maker based in Harlingen. I could not find biographical information about him (except for a photo from an filmed interview), but this violin clearly speaks of an experienced hand showing mastery of important aspects of fine lutherie. I'm particularly impressed by the exceptionally fine tracing of the purfling and outstanding cornerwork.
This violin needs attention to two things:
Firstly, and importantly, it has a considerable soundpost crack in the top. Although stabilised with cleats and gluing, this should get a complete soundpost patch inside.
Secondly, the corner by the bass F in the top is broken off and the corner should be rebuilt. Although this has no tonal implications, I feel that this is a structural and aesthetic fracture that needs attention.
Other than the above, this violin is in impeccable condition and I don't doubt that, after restoration, it would serve well professionally for many years to come.
It is offered as is.