For the thoery of microscopes and how lens work, refraction etc The the Beekeeping in a Nutshell Number 9 Microscopy for Beekeepers by Peter Jewel is good. It covers things in simple to understand and more than enough detail for the exam.
Hard to find in print thought these days.
For the practical side, much of the stuff taught is a bit outdated. When I took the course they were insisting we used Xylene mountants with no fume cabinets and boiling test tubes with Sodium Hydroxide inside them, Oh Boy, Health and Saftey would have had a field day. I had all sorts of problems getting them to accept that modern aqueous mountants where fine.
Practical Microscopy for Beekeepers by Bob Maurer looks good. I don't own a copy but having browsed a copy, it seems to be more up to date than most. Avoid Microscopy on a shoe string.
Pollen Identification by Rex Sawyer is a must.
As is Anatomy and Dissection of the Honey bee by Dade.
Any specific question please ask.