Duce, D. A.Liere, R vanHagen, P.J.W. ten2014-10-212014-10-2119901467-8659https://doi.org/10.1111/j.1467-8659.1990.tb00371.xThis paper shows how a formal description of the GKS input model can be extended to include hierarchically structured input devicesAn Approach to Hierarchical Input Devices10.1111/j.1467-8659.1990.tb00371.x15-26