PERSI stands for The Periodical Source Index which is an index to more than 1.9 million genealogical articles from more than 6,500 periodicals published in America, Canada, Britain, and Ireland. The time period cover 1800 to the present and some articles from the 1700s. This largest subject index to genealogical and historical periodical articles was created by the Allen County Public Library in Fort Wayne, Indiana.
PERSI can be searched online through the King County Library System if you have a library card. PERSI is indexed by locality and surname. While PERSI is very comprehensive, not every surname in an article is included in the index, only the main family being researched. The Family History Libraries also have PERSI on microfiche. In addition, PERSI can be found on Ancestry.com (fee subscription).
Although one can order a photocopy of an article directly from the Allen County Public Library, there is a fee and it takes time to receive the copy. Take advantage of your public library and request an interlibrary loan for the desired magazine. This can be done for free and will probably come more quickly.