City of Ventura, California, Home & Neighborhood Safety: Cluster MailboxesArchived 2012-02-02 at the Wayback Machine, retrieved 23 January 2012: "Cluster mailboxes are those that house mail receptacles for several residences...They make particularly attractive targets for thieves, as once the back of the box is breached, all of the individual sections become accessible and mail from many households can be taken in a very short period of time."
Bruns, James H. (July–September 1996). "Soap boxes won't do". EnRoute. National Postal Museum. Archived from the original on 28 May 2003. Retrieved 23 September 2014.
Bruns, James H. (July–September 1996). "Soap boxes won't do". EnRoute. National Postal Museum. Archived from the original on 28 May 2003. Retrieved 23 September 2014.
City of Ventura, California, Home & Neighborhood Safety: Cluster MailboxesArchived 2012-02-02 at the Wayback Machine, retrieved 23 January 2012: "Cluster mailboxes are those that house mail receptacles for several residences...They make particularly attractive targets for thieves, as once the back of the box is breached, all of the individual sections become accessible and mail from many households can be taken in a very short period of time."