Gustaf Tenggren's sketch of Snow White in the dark forest is one of the most striking of all the prints.
Sold in auction on August 21, 2011 for $155.35 (USD).
The Disney and RKO copyright info in the lower corners of the photo.
Here's the classic log crossing with Tenggren's Dwarfs.
A few others in the series.
The entire set of 20 promo stills can be seen on the lower half of this page from the 1937 "New Edition" Snow White pressbook. Also pictured are eight 11x14 stills which we posted in another Archive entry.
Images via Heritage Auctions.