Here are scanned (pdf) versions of two papers Peter Ash and I wrote on Dirichlet Tesselations:

Recognizing Dirichlet Tessellations, Geometreia Dedicata, 19, 1985, 175-206.

Generalized Dirichlet Tessellations, Geometreia Dedicata, 20, 1986, 209-243

Kluwer publishes Geometria Dedicata. We trust they won't mind our making this old stuff available.