"Definitions of bullying at work further emphasize two main features: repeated and enduring aggressive behaviours that are intended to be hostile and/or perceived as hostile by the recipient (Einarsen and Skogstad, 1996; Leymann, 1990b; Zapf et al., 1996). In other words, bullying is normally not about single and isolated events, but rather about behaviours that are repeatedly and persistently directed towards one or more employees. Leymann (1990b, 1996) suggested that to be called 'mobbing' or bullying, such events should occur at least once a week, which characterises bullying as a severe form of social stress. In many cases this criterion is difficult to apply because not all bullying behaviors are strictly episodic in nature. For example, a rumour can circulate that may be harmful or even threaten to destroy the victim's career or reputation. However, it does not have to be repeated every week. In cases we have been made aware of, victims had to work in basement rooms without windows and telephone. Here, bullying consists of a permanent state rather than a series of events. Hence, the main criterion is that the behaviours or their consequences are repeated on a regular as opposed to an occasional basis."