Grettler, D. J. (1995). Landowner and tenant opportunity in seventeenth century central Delaware: Final archaeological investigations at the Richard Whitehart (7K-C-203C) and John Powell (7K-C-203H) plantations, State Route 1 Corridor, Kent County, Delaware. [Dover, Del.]: Delaware Dept. of Transportation.

Grettler, David J. Landowner and Tenant Opportunity in Seventeenth Century Central Delaware: Final Archaeological Investigations At the Richard Whitehart (7K-C-203C) and John Powell (7K-C-203H) Plantations, State Route 1 Corridor, Kent County, Delaware. [Dover, Del.]: Delaware Dept. of Transportation, 1995.

Grettler, David J. Landowner and Tenant Opportunity in Seventeenth Century Central Delaware: Final Archaeological Investigations At the Richard Whitehart (7K-C-203C) and John Powell (7K-C-203H) Plantations, State Route 1 Corridor, Kent County, Delaware. [Dover, Del.]: Delaware Dept. of Transportation, 1995.