Second-Level Narrowing

You consult a couple of encyclopedia articles on WWII weapons and discover that the general categories of weapons at that time were tanks, artillery, and firearms.

Each of these categories includes several dozen to several hundred specific weapons.

Can you cover all of these in one paper? Sure, if you write a sentence on each one. But then you’re not really writing a research paper; you’re writing a list. You need to go deep, not wide. No one, including you, wants to read a paper that treats a great deal of material in a very superficial manner.