The modern era of resuscitation began in 1960 with the publication of the classic paper by Jude, Kouwenhoven, and Knickerbocker on closed chest cardiac compression, which showed that the circulation could be maintained during cardiac arrest without the need for thoracotomy. A few years earlier Elam, Safar, and Gordon had established expired air ventilation as the most effective method for providing artificial ventilation for a patient who had stopped breathing. The effectiveness of closed chest defibrillation had been demonstrated by Zoll a few years earlier. By combining the techniques of chest compression with expired air ventilation, it became possible to maintain the viability of a patient in cardiopulmonary arrest until a defibrillator could be brought to the scene. Special units were established that were able to resuscitate patients at high risk of developing cardiac arrest, and special hospital cardiac arrest teams were created.