There's not much point in buying an Intel assembly language book to help with learning assembly language for ARM. Though many concepts are the same there's too big a difference for the Intel book to be worth it's money. It's not like buying a VC6++ book to help with eVC++ 3 where so much is similar.
Here's a site I found for you. It has all the basics
I'm looking at the assembly language in PocketGL as I write this ( it's my first look at ARM assembler ). Many of the instructions are the same as you would find in any online assembly article ( add mov sub bne ). Other than the ARM assembly docs which will give you info on the commands & registers you need to know about the memory locations on the hardware some of which you can get from existing ARM coders.
The really good news is that assembler is miles easier to understand than C++ as there's no complex contrived syntax to worry about. You do need to document much more. I document every single line of assembly.
(I am one of the small band of people on PocketMatrix who have been writing games for 20 years or more so I've written more assembly language than most people ever will mostly for Motorola & Intel chips)