Journal articles and other periodical publications provide scholarly information on specific aspects of history and the history of science.
1) Because scholarly articles are peer reviewed, they are more authoritative than magazine articles.
2) Since articles are published on a shorter schedule than books, they can be more-up-to-date.
The following indexes are the best ways for you to identify journal articles:
Watch for these authoritative journal titles when you are searching indexes and scanning footnotes. You can also browse the latest issues online or in paper because it takes some time for indexes to add newly published articles:
There are also indexes devoted to literary history, philosophy and art history that may be of use for specific topics:
Usually researchers find more sources by looking at the footnotes in an article or book, but these will always be older than the publication you have in hand.
Citation indexes like the Web of Science (which includes sections for the Social Sciences, Arts and Humanities, and Science) are set up to search for sources cited in the footnotes of journal articles as soon as they become available.
This allows you to find newer articles which cite the books and articles you already know are key for your topic. By relying on connections between authors rather than subject words and by moving forward in time, citation searching can open up new avenues of research.