I have more bookcases I have made and will try to get pictures soon.  This set is solid 7/8 inch oak with glass shelves of adjustable height.  I have recently constructed another set of shelves.  This new set does not have adjustable shelves and is completely red oak (shelves and all).  The new set was designed for heavy storage.  The frame is constructed from full 1" rough cut (it is greater than 7/8" thick) and the shelves are just over 3/4" thick.  Each shelf support frame is securely fastened to the outside frame.  The new unit does not creak or give at all due to the over-engineering I incorporated into the design.