Mid Century Sectional Bookcase with Sliding Glass Doors

Vintage mid century solid hardwood stacking library bookcase shelves by Simplex, made in the 1960's probably. There are four modules, each with two sliding glass doors. The lowest one has a little plinth underneath; it and the next one up are deeper than the other two. The top two are a bit taller and have a single, adjustable shelf inside. There are bars which turn to hold each part in place. Not sure what the timber is: possibly teak or similar, but they are all solid wood; only the back boards are plywood.