I am studying GW theory (and DT theory) in algebraic geometry. I now understand the heuristic "Aut, Def, Obs" argument written in Mirror Symmetry book (by Hori et al.), but it is too hard for me to read for example "Intrinsic normal cone" by (Behrend and Fantechi). It seems to me that these is a big gap between the heuristic explanation and rigorous arguments in deformation theory in these foundational papers.
Could anyone suggest good background reading materials for this area? I am aware of the standard Hartshorn's book.