On the Kronecker products of irreducible representations of the 2×2 real unimodular group. I
Lajos Pukánszky · Transactions of the American Mathematical Society · 1961
When speaking of unitary representations in this paper, we mean always representations, which are strongly continuous.Bargmann's classification was performed under certain restrictive conditions (cf.[l, (5.6.),p.601 ]).It has been proved, however, that these conditions are automatically fulfilled, cf. for instance, [6, p. 545].(2) Oral communication.(3) At the time being only the first part, dealing with the product of two representations of the principal series [lO] is accessible to us.