[1] Bulgarian Acad Sci, Inst Populat & Human Studies, Sofia 1113, Bulgaria
[2] Sofia Univ St Kliment Ohridski, Psychol Dept, Sofia 1504, Bulgaria
[3] Sofia Univ St Kliment Ohridski, Dept Sociol, Fac Philosophy, Sofia 1504, Bulgaria
[4] Univ Warwick, Warwick Business Sch, Coventry CV4 7AL, England
[5] Sofia Univ St Kliment Ohridski, Fac Philosophy, Dept Psychol, Sofia 1504, Bulgaria