Time Period

Each database differs in terms of:

• the publication dates of the materials included
• how frequently the database is updated

For example, notice the different time periods described for the magazines and journals in the database shown below:

Some databases, such as those created by ProQuest and EBSCO, index every article in every issue of a specific publication. Databases that index every issue of a magazine each time it is published may indicate publication dates.

Some databases, such as SIRS Knowledge Source and Opposing Viewpoints in Context, select the articles they index from a variety of sources but do not index every issue of a periodical, so they may only indicate the date that they update the material in the database.