"Ethics, copyright laws, and courtesy to readers require authors to identify the sources of direct quotations
and of any facts of opinions not generally known or easily checked."
--Chicago Manual of Style, 15th edition (Chicago: Chicago Univ. Press), p. 594
When doing research, it is necessary to consult and gather information from a variety of places and authors. Therefore, it is important to cite the author (and the work) for a variety of reasons: