[en] Nuclear double-beta (ββ) decay may proceed via several theoretical scenarios, but only the two-neutrino (2ν) decay mode, allowed by the Standard Model (SM) of the electroweak interaction has been up to now observed experimentally. However, theories more general than the SM, predict that the (ββ) decay may also occur without emission of any neutrino. The parameters connected to the physics beyond the SM, appearing in the theory of (ββ) decay, depended decisively on the relevant nuclear matrix elements which have to be evaluated theoretically. The models for calculating these matrix elements are mainly based either on the Shell Model or the proton-neutron quasi random phase approximation (pnQRPA). In this paper we give a critical review of the QRPA- based methods used in the computation of the nuclear matrix elements for the (ββ) decay, stressing on second-QRPA and renormalized-QRPA approaches which go beyond the quasi boson approximation. Calculations of 2νββ decay matrix elements for the case of ⁷⁶ Ge with the pnQRPA, second-QRPA, RQRPA and full-RQRPA methods, using two different choices of the single particle basis, are reported. (authors)