“…The remaining 23 documents, which fulfilled all inclusion criteria, reported the results of 11 independent studies. Only 15 of these 23 documents were needed to provide all relevant information about the 11 studies reviewed in this article (Beermann et al, 1999; Ducki et al, 1998; Friczewski, 1994a; Friczewski et al, 1990; Konradt, Schmook, Wilm, & Hertel, 2000; Lück, 1999; Müller & Münch, 1997; Münch, 1996; Pluto, Nolting, & Zober, 1997; Riese, 1998; Rudow & Demuth, 1997; Slesina, 2001; Sochert, 1998; Wellendorf, Westermayer, & Riese, 2001; Westermayer & Wellendorf, 2001).…”