I'm building some 7' by 3' bookcases with mix of plywood and solid oak for the sides and back (mostly plywood), but full solid oak shelving for strength. I'm worried that the ~9" depth to the shelves will allow up to about 1/8" of movement. If I used the online formula correctly. Since the sides and shelves are constructed so differently, and will thus move differently, I'm assuming I can't just secure the fixed shelves to the sides and back.
My primary question is: am I right about the movement, and if so, is it sufficient to place the fixed shelves in a dado and only glue the front couple inches? (I want the front of the fixed shelves to look solidly attached throughout the year.) Secondarily, can I "hide" the movement at the back, for instance by running a 1/4" dado and only insert the first 1/8" inch during construction (it's winter, so it's probably near my low humidity point)? I didn't plan quite far enough ahead to select my boards for grain direction, so I'm assuming the worst.
Here's a rough look at my design, for reference; green is plywood, and the rest is solid. The topmost and bottom visible shelf, as well as one not visible near the very bottom are the fixed shelves I'm asking about attaching. (The rest of the shelves will be adjustable, so I just need to allow room for their largest size, and accept some gap.)