I need a REALLY strong drywall anchor.

I use the EZ anchors a lot for pictures, and other light to moderate stuff

I want to put up some shelves for books, 24" wide and 10" deep using some small-ish, unimposing brackets. Unfortunately, the studs are just not in convenient locations.
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Is there anything out there that can hold a lot more than the usual 30 lb. anchors? I recently came across the Toggler SnapScru and the EZ anchor version which look promising. They say they hold up to 75 lb, but that is shear strength, and I need "pull" strength as well.

Any experience with these? Anything else out there?