Herbert Weir Smyth, A Greek Grammar for Colleges

γὰρ δή for of course, for indeed, for you must know, as φαμὲν γὰρ δή for of course we say so.

γὰρ δή που for I presume, for doubtless.

γὰρ οὖν often of frank assent, as οὐ γὰρ οὖν certainly not, λέγω γὰρ οὖν certainly, I do say so; less often to explain (for certainly); καὶ γὰρ οὖν (not very common) is stronger than καὶ γάρ.

γάρ που for I suppose.

γάρ τοι for surely, for mark you; sometimes καὶ γάρ τοι.