Vintage 40's?? Sawn Oak Secratary Drop Front Desk

Very nice drop front desk has cubicles with small drawer and 3 bottom drawers, beautiful original hardware ALL LOCK WITH INCLUDED SKELETON KEY. We did some research on wood and ASSUME the desk is made of sawn oak giving it the ribboned grain look. It is also quite heavy. There is a stain on the top where the finish has been like bleached away?? Otherwise the desk is in very nice condition. One drawer is loosened at its joint to the bottom of the drawer.
The desk has been in the family since the 60's that we know of, could be longer. There are no markings that we can find other than the stamp on the highest wood panel on the back, not sure what this means. We would be interested in knowing the value to possibly sell the desk??