Please help identify this painting/painter

Large painting (3 ft by 2 ft) of the edge of either a swamp or pond. Three large trees on the left, one on the right. The trees are primarily done in black, with the background primarily a mint/olive green and a pinkish tint to the sky. Painter's signature is "NANSEN," and the name Nansen is also on the back of the canvas with the identifying number EH 3H. The painting is rather old and the canvas is very fragile, but aside from that I'm unsure as to the approximate age of the painting. I can send pictures for further identification.