The interplay of the disc and the dark halo resonances governs the secular evolution of disc galaxies, and the properties of their bar component (Athanassoula 2002). Martinez-Valpuesta et al. (2006), Ceverino & Klypin (2007) and Athanassoula (2007b) confirm and extend this work. Ceverino & Klypin (2007) calculate the orbital frequencies of each particle over the whole temporal evolution, and thus find much broader frequency peaks. In all cases, it is the same resonances that come into play, and, as in Athanassoula 2002, the angular momentum is emitted by near-resonant material in the bar region and absorbed by near-resonant material in the halo and the outer disc. The relative importance of each resonance, however, varies from one case to another. Furthermore, the second and third of the above mentioned studies examine the location of resonant orbits in configuration space and find compatible results.