Integrable and superintegrable systems associated with multi-sums of   products
  We construct and study certain Liouville integrable, superintegrable, and non-commutative integrable systems, which are associated with multi-sums of products. 
Peter H. van der Kamp, Theodoros E. Kouloukas, G. R. W. Quispel, Dinh   T. Tran and Pol Vanhaecke
nlin.SI