The items in this section are intended to help the researcher find useful information on ancient philosophy. Items designated "reference works" usually are not expected to contain material of such depth and subtlety that they would be of use only to experts in the field; rather, they are meant to provide information of general import (dates, definitions, overviews) for those who may just be starting out in their studies, for those who simply need refreshers and summations, or for those trying to win a bet. Some reference works, however, provide more in-depth coverage than others; the following list will indicate the intellectual density of each item in the annotations. Remember that reference sources are often a good starting-point for research because the bibliographies at the end of each entry (in the case of large encyclopedias) or the entire resource will direct you to valuable primary and secondary material.