Looking around for some books on medieval arms and armor – including details about polearms, and not necessarily with gaming application – I found the following books via Amazon. What do you think? Other books you want to suggest? Warnings? Is this series from St. Martin’s Press good?
Or start with some books from other lists? 
I got recommendations for Gary Gygax’s World Builder and The Palladium Book of Weapon and Armour via Twitter. What do you think of these?