Trees of multidisks as Gromov boundaries of amalgamated products
  We describe, under some additional technical assumptions, the Gromov boundary of the free product of several $G_i$'s amalgamated wrt. $H$, where $G_i$ are hyperbolic groups with boundary homeomorphic to a densely punctured $n$-sphere, and $H$ is their common subgroup corresponding to a peripheral sphere in each of the $\partial G_i$'s. 
Dominika Pawlik, Aleksander Zab{\l}ocki
math.GT