OpenAccess usually adds the references if you use the "Enable Project" wizard.
You can also try the menu in VS: "OpenAccess > Configuration > Check Settings" this will alert you to any old assembly references.
If you want to do it manually:
Telerik.OpenAccess.dll
Telerik.OpenAccess.Adonet2.dll
Telerik.OpenAccess.Runtime.dll
Telerik.OpenAccess.35.Extensions.dll
Telerik.OpenAccess.Config.dll
Telerik.OpenAccess.Web.dll
Telerik.OpenAccess.Windows.dll
If you are on VS2010 and using 4.0 framework, include Telerik.OpenAccess.40.Extensions.dll