Experimental data demonstrate that the enhancement associated with the quasi free kinematic conditions in nuclear reactions is one of the most prominent features in a large energy interval. The experimental data on A(x, bx)B reactions have been analysed using various models: plane wave and distorted wave impulse approximations (PWIA and DWIA), modified simple impulse approximation (MSIA), several modifications of PWIA, higher order corrections in particular S-state final state interaction modifications of the PWIA, unitarized version of the truncated multiple seattering series and the AMADO model.