The major diffraction peaks of my sample have essentially the same 2θ values as the reference (graphically), but have different heights. Can it still count as conclusive evidence that my sample matches the reference? Or does it suggest that my sample is a different substance? Also, as a side question, can you suggest any good, up-to-date and free reference text books (or any other sources) that I should read up to master XRD analysis? The one I'm reading right now is from 1956. I'm kind of new to the research field. I would really appreciate your help. Thanks!