Popular health literature is aimed at a wide audience and does not presuppose subject expertise on the part of the reader. Popular literature typically is written by journalists or science writers, but sometimes also by scientists, medical experts, or scholars in non-medical fields. In addition to works that explain scientific and health issues to general readers, popular literature includes genres such as investigative journalism, essays, personal narratives, and polemical works. Popular literature has research value for historians, medical sociologists and medical anthropologists, since it may influence health behaviors and viewpoints, and capture dissenting viewpoints not found in scientific, technical and medical publications. The Library collects popular literature highly selectively, with emphasis on works noted for their impact on individual behavior or public policy, publications written by noted experts, or those with content or perspective not found elsewhere in the literature.