The modern classical guitar compositions are an even greater challenge to tackle than older pieces since they demand a very committed interpretation and feature dissonances, unorthodox techniques and a hint of poetry in their approach. The works of Paraguayan composer and guitarist Augustin Barrios Mangore combine classical influences and folkloric music for a result that will require you to venture into unknown territories, which is obviously the best way to enrich your playing. The nine pieces to work on that songbook should do exactly that.