# Unbounded, 2-dimensional knapsack problem

I have the following problem:

There is rectangle with fixed $$W > w_i$$ width and $$H > h_i$$ height. Given a set of item types, where each type has some $$w_i$$ width, $$h_i$$ height and $$v_i$$ value. I would like to maximize the value of the items placed in the rectangle.

An item can be placed as many times as needed. Not every type has to be present in the optimal solution. Two items can not overlap.

Is there any literature available for this (or a similar) problem? Is there a name for this problem? I didn't have luck with finding info on optimizing inside a 2-D region.