I've searched high and low for a terse (yet complete) introduction to the foundations of non-relativistic QM. Shankar is unparalleled in terms of completeness, yet it is infuriatingly verbose. Landau's presentation is a bit dated and difficult to follow in many instances. It is also not as mathematically rigorous as I'd like. I'd say Ballentine has come closest to satisfying my aforementioned requirements, although it has many subtle errors (at least in its first couple of chapters). Are there any books I've missed in my search?