@iyanu
These are the books that I studied for the exam.
Clinical Laboratory Science Review: A Bottom Line Approach by Patsy Jarreau (it is summarized but I find lacking in Blood bank and Clinical chem)
For Blood bank transfusion and Clinical chemistry, I supplemented it with:
Success!Clinical Laboratory science by Ciulla
Concise Review of Clinical Laboratory science by Hubbard
I did not read the whole Ciulla and Hubbard book, just the sections on Clinical chemistry and Blood transfusion. As for the histology part, I just searched the internet about the basics on histology and what you need to know as a med lab scientist.