The years 1961 to 1981 were set as boundaries for this volume because the author's initial research revealed that a twenty-year span was a manageable unit, because the novels published between those dates yielded abundant materials for such a reference work, and because significant changes in the way portraits of adolescent females were being drawn took place during the period - for example, sex-role stereotyping became a shade less prevalent, young women's sexuality was discussed more forthrightly, and some topics (such as single women's pregnancies and lesbianism) were treated more overtly, sometimes less judgementally.