The Chicago Manual of Style presents two basic documentation systems: (1) notes and bibliography and (2) author-date. Choosing between the two often depends on subject matter and the nature of sources cited, as each system is favored by different groups of scholars.
The MLA Handbook is published by the Modern Language Association, the authority on MLA documentation style. Widely adopted by universities, colleges, and secondary schools, the MLA Handbook gives step-by-step advice on every aspect of writing research papers, from selecting a topic to submitting the completed paper.
APA Style® originated in 1929, when a group of psychologists, anthropologists, and business managers convened and sought to establish a simple set of procedures, or style rules, that would codify the many components of scientific writing to increase the ease of reading comprehension.