I have a really hard time learning Double Integrals, which I attempted to understand when I first saw the use of polar co-ordinates for Integrals. So my goal is to learn double Integrals and also learn how polar co ordinates is being applied. I'm looking for a book that goes step by step, and which teaches me things like how $dx dy$ changes to $r dr d\theta$, (this is only one example) etc (everything).
In short I'm looking for something like "Double Integrals with polar co-ordinates for dummies"
Please help me. Thanks.