NFPA 1221 Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems, 2007 ed. (Std: Install, Maint, and Use of Emr Srvc Commun - Amer) {391 NFC}
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}