Music Theory For Beginner
Exact same question asked and answered in the theory forum just a couple of days ago.
BTW, theory is theory, regardless of instrument so don't limit yourself to "bass theory" books. A C chord is C E G no matter what instruments are playing which combinations of those three notes. Our job is to define the harmony so that's what we need to know- harmony and how it works. Go check out that other thread and use that to guide you to useful books.
Also, search the theory forum for other threads that'll help you find a TON of resources because this kind of stuff pops up there pretty regularly on the theory forum.
John