Hans von Luck's memoir Panzer Commander has some insight from his point of view as part of the forces trying to respond to D-Day. You have to be a little careful due to his desire to whitewash some things, but he is pretty honest on the tactical level. His comments about aerial interdiction could be interesting for your paper, as the air war sometimes gets overlooked.

Considering the fact that you write a paper i assume you need some primary data. The, without a doubt, best book for primary data on the German side of the Normandy campaign is Niklas Zetterling "Normandy 1944: German military organization, combat power and organizational effectiveness. The book doesn't include strategy or expectations of the German side but the collected primary data should allow you to present your own conclusions on what the Wehrmacht was expecting. Moved troops, ressources et cetera are included and should help you drawing a picture. The book is a must have since it offers what no other author does.

While Zetterlings book is unique there are plenty of books dealing with the Wehrmacht and the reactions and actions of German Commanders. I liked "The Germans in Normandy" it gives you a general feel what people like Rommel and Kluge were "thinking" during the campaign.

Generally i feel that alot of books give a good picture of the German side even if they were written with a focus on the anglo-american side.

Edit: Since you write a paper i assume you already stumbled over the No2. Operational Research report for the 21st Army group.

I would recommend, if you have a nuanced eye, to read Hubert Meyer's 12.SS multi-volume chronicle of the Normandy campaign. Meyer was a member of HIAG and an unapologetic Nazi to the end, but is shockingly frank about the Normandy experience. The absence of charges does not mean the absence of guilt.

At the very least, his position as the Ia of the 12.SS gives a contemporary mindset of a staff officer on the front-lines.