yeah, 3 bunnies has calcium info/HRS has oxalic acid info.
spinach, mustard greens and parsley are on both lists; however, carrot tops and kale (and possibly others - I haven't really looked in a while) aren't high in OA and aren't listed as things that should be limited on the HRS site. they ARE listed as things that should be limited on 3 bunnies, though. how limited the "high calcium but not high OA" veggies need to be depends on the age of the bunnies (matters less in little ones in the 12 week-7 mos range 'cause they're growing) and the individual rabbit's tolerance for calcium.