I've been looking for some good resources on integrals in four-space (SR and GR), and hope someone can suggest some! I'm not too interested in abstract mathematical formalisms to the extent of pure math though, I must keep in mind that this is all to do with physics (at least for me!). I know there are 4 kinds of integrals one can do in four-space: (1) Integrate a line element, ie. a curve. (2) Surface integral on a 2-D surface. (3) Integral on a 3-D hypersurface. (4) 4-D volume integral. Landau-Lifgarbagez gives a brief intro in their field theory book but I'd like to clear some things up instead of just having formulae presented to me. Any suggestions??? Cheers guys!!