Research reviews can vary a great deal in emphasis, style and presentation. They can focus on the contemporary situation, or incorporate a historical perspective (Kessler-Harris, 1982; Reskin and Padavic, 1994; Hakim, 1996). They may seek to establish enduring patterns and relationships that are not specific to any historical period (Lester, 1983), or cross-cultural comparisons may be undertaken to establish the effects of cultural factors as well as historical factors (Milner, 1983; Hakim, 1999a).