TY - JOUR T1 - Defining frequent use of an urban emergency department. JO - Emerg Med J PY - 2007/06/01 AU - Locker TE AU - Baston S AU - Mason SM AU - Nicholl J ED - DO - DOI: 10.1136/emj.2006.043844 VL - 24 IS - 6 SP - 398 EP - 401 Y2 - 2024/12/27 ER -