You probably can't find any definitive information, because there's really no hard and fast rule. Owners will have different views and also a lot depends on the rabbits and what their digestive systems will tolerate.
What are you feeding them at the moment? How large are they and how old?
I can give you my view and tell you how I feed my rabbits, but I expect that there will be alternative opinions.
I would guess that around 85% of my rabbits' diet is hay and grass. That probably is fairly consistent all year round. Out of the remaining 15%, I feed a small amount of pellets (more in the Winter than the Summer). The remainder is made up of forage, herbs, tree leaves/twigs and vegetables, most of which I grow in the garden. The time of year will play a part and will mean that in the Winter they receive more vegetables and less forage (I don't dry forage) and in the Summer they get mostly herbs and forage. I have three rabbits, who eat a lot and fortunately don't seem to have digestive issues. I always try to feed a selection of different items to provide a variation of nutrients.
Herbs and forage are generally tolerated more easily than vegetables and provide a similar amount of fibre. They are also very popular with rabbits, especially the stronger-smelling herbs. Sometimes members of the Brassica family (cabbagey things) will lead to problems with some rabbits, as they can cause gas.
I think you can only really go by trial and error. I've never weighed what I feed, but I think it's probably a lot more than 50g each, but you need to find an amount that suits your rabbits. A good indication of how well their digestive system is working of course is to monitor their poo