The Canadian Entomologist
To this family belong the potter wasps. They differ from the paper-making wasps in being solitary and in constructing their nests of mud or clay, instead of macerated woody fibre or pulp. It is perhaps one of the largest, if not the largest, families in the Vespoidea, and is well represented in all parts of the world by many genera and species.
Ashmead, William H., "Classification of the Fossorial, Predateous and Parasitic Wasps, or the Superfamily Vespoidea No.7" (1902). An. Paper 85.