rare painting of a German expressionist nude, Circa 1910/1920

Extraordinary and rare painting of a German expressionist nude, Circa 1910/1920.

The explanation of this work speaks for itself.
The subject is particularly daring for the time, right in the pre-war German Expressionism.
This work, and subject, is to be compared to those of Max PEICHSTEIN or Ernst Ludwig KIRCHNER.
A particularly interesting work, but we do not know the artist.
The painting is in excellent condition, well fixed to the canvas, there is a small tear to the left of his navel.
The canvas deserves tension, and the painting needs a big cleaning.
this painting was purchased in Berlin, for the last time, in the early 2000s.
No signature, but there are two labels two-thirds torn off, at the back of the frame, perfectly illegible but probably evoking the same painter's name.

Nice dimensions: 75cm high and 65cm wide.