Three-frequency resonances in dynamical systems
  We investigate numerically and experimentally dynamical systems having three interacting frequencies: a discrete mapping (a circle map), an exactly solvable model (a system of coupled ordinary differential equations), and an experimental device (an electronic oscillator). We compare the hierarchies of three-frequency resonances we find in each of these systems. All three show similar qualitative behaviour, suggesting the existence of generic features in the parameter-space organization of three-frequency resonances. 
O. Calvo, J. H. E. Cartwright, D. L. Gonzalez, O. Piro, & O. Rosso